FILE

CATEGORY

QUESTION SYNOPSIS
1
MechanCan you explain to my husband and my brother why thin tires produce more traction than wide tires and why race car drivers prefer wide tires with no tread over thin tires with deep treads. I have tried many times with the typical male response "you don't understand racing." They seem to think that race drivers like the wide, treadless tires because they produce more traction. Duh!! Can you explain in terms that they would understand? I give up.
3
MechanWhat is the maximum acceleration a car can undergo if the coefficient of static friction between the tires and level ground is 0.80?
6
Mechanwe are supposed to build a contraption to hold an egg that is light and will prevent an egg from being broken when put in the contraption and dropped...Do you have any suggestions on successful ways to build this?
7
MechanA 50kg high wire artist carries a weighted pole as illustrated. Her center of gravity is 80cm above the high wire and the two 23kg masses are located 120cm vertically below the wire. Find the vertical location of the center of gravity of the walker and the weighted pole relative to the high wire. Is this case of stable or unstable equilibrium.
9
MechanHow long would a 100W light bulb burn, on weighing 140g(if the mass was converted to energy)?
11
MechanA man and a bicycle have a total mass of 100 kg. He is cycling at a constant 8m/s up a hill that makes a 4 degree angle with the horizontal direction. What power must the rider expend against gravitational forces?
12
Mechanwhat is acceleraton
13
MechanAn airplane travels 80m/s as it makes a horizontal circular>turn which has a 0.80-km radius. What is the magnitude of the resultant>force on the 75- kg pilot of this airplane (in kN)?
15
Mechane have the length of a car tire's skid mark. We are guessing that the co-efficient of friction for car tires is about .5 or so. What is the proper formula for the calculating of the velocity of this vehicle?
16
MechanA wheel is being rolled along a level path with a constant speed of ten m/s. A small lump of mud stuck on the wheel suddenly breaks losse when it is at the top of the wheel. If the wheel has a diameter of two m, how far ahead of the axle is the lump when it strikes the path?
17
MechanIf you had to decide between regular width tires with no treads or tires with (both are called slicks), which would you choose for better breaking ability? In drag racing, wide slicks are prefered for the rear tire's, why?
18
Mechan Do things of different weight fall at the same speed when dropped from the same height? Will they fall at the same time on the ground?
21
MechanI want a picture of the insides of a photocopier. I realize that this is not as easy as just putting a mirror on the machine. I doubt that the reflection of the inside will come out as an image. I am thinking that it may come out all black. Or will it? I was hoping that you could explain exactly what does happen.
23
MechanHow much work is done by a person lifting a 2.0 kg object from the bottom of a well at a constant speed of 2.0 m/s for 5.0 s (in kJ)?
24
MechanA 5000 LB AIRPLANE LOOPS AT A SPEED OF 200 MI/HR. fIND THE RADIUS OF THE LARGEST CIRCULAR LOOP POSSIBLE, AND THE FORCE ON THE PLANE AT THE BOTTOM OF THE LOOP.
26
MechanI am most obliged if someone can clear my doubts on pulley system:1. Why is a movable pulley more efficient than a fixed pulley? 2. What governs the efficiency of a movable pulley system?
27
MechanI think this question is Kinematics...A jet pilot sets his compass due east. After 30 min, during which he maintained a constant speed of 400km/h with repect to the air, he finds himself flying over a city located 220 km east and 20km south of his point of departure, Determine the wind velocity in magnitude and direction.
28
MechanHi! I'm building an egg car for physics. Dropping something weighing 1 kg. from 1 meter, my car (with an egg as its passenger) must go exactly 6 meters. I must also utilize a braking system. Any ideas?
29
MechanA tennis ball is thrown from ground level with velocity Vo directed 30 degrees above the horizontal. If it takes the ball 1.0 second to reach the top of its trajectory, what is the magnitude of the initial velocity?
30
MechanA 60 kg woman bends 90 degrees forward from the waist, keeping her legs vertical. The centre of gravity for her upper body is located 70 cm from her hips. If two-thirds of her mass is in her upper body, how far forward from the line of her legs is her new centre of gravity?
31
MechanA ball rolls off a cliff that is 10 m high. If the ball lands 5 m away from the edge a. how long does it take to hit the ground? b. what is it's initial speed? c. what will be it's final velocity (give both the magnitude and direction)
32
MechanWilly obtains an inclined plane with theta= 36.9 degrees and length s=1.00 m. He releases block A from rest at the top of the plane at the same instant he relases and identical block B from te bottom with an initial speed Vo. Willy observes that just before the blocks collide, their speeds are equal and opposite. The coefficient of kinetic friction between blocks and plane is Uk=0.3. How far up the plane in cm did this collision occur?
34
Mechan30. An oar is held by a rower at .35m from the oarlock. The oar makes contact with the water at an average of 1.3 m from the oarlock. If the force applied by the rower on the oar is 80N. what is: a)the force of the oar on the water, and b)the force on the oarlock. the anwers are a) 22N and b) 100N I need to know the method to getting the answer correct!!!
35
MechanSliding friction is more than rolling friction because
37
Mechangiven angular velocity, time and radius how to you figure distance along the perimeter?
38
MechanAt room temperature, an oxygen molecule, with mass 5.31 x 10-26 kg, typically has a KE of about 6.21 x 10-21 J. How fast is it moving?
39
MechanA 0.5 Kg rock is tied to a 75 cm string and a person swings it ina vertical circle. The rock goes around at a constant 1.5 revolutions per second. 1. determine the tension in the string when the rock is at the top of the circle. 2. at the bottom of the circle. 1 rev = 2 PI
40
MechanTwo identical balls are traveling toward each other with speeds 4.0 and 7.0 m/s, and they experience an elastic head-on collision. Obtain the velocities (magnitude and direction) of each ball after the collision.
43
MechanOk, I'm studying physics over the summer on my own, and I bought the text book, but sometimes the answers in the book don't seem reasonable. I'd like a 2nd opinion. The question is: "Agent Tim, flying a constant 185 Km/h horizontally in a low-flying helicopter, wants to drop a small explosive onto a master criminal's automobile traveling 145 Km/h (same direction) on a level highway 88.0 meters below. At what ANGLE (with the horizontal) should the car be in his sights when the bomb is released?" By using the formula:[ TAN(-1)angle = -9.80 t / horizontal velocity ] ........ i get -75 degrees. Answer in book is -61.8 degrees. am i wrong, or is the book wrong?
44
MechanHow do you convert from grams to newtons? In my case, there is 50 grams.
48
MechanThe radius bone in a forearm has an average effective cross-sectional area of 1.33 x 10 to the -4 meters squared. How much compressive force can it withstand before fracturing?
49
MechanA Boeing 747 Jumbo Jet has a length of 57m. The runway on which the plane lands intersect another runway. The width of the intersection is 25.0m. The plane decellerates through the intersection at a rate of 5.70 m/s^2 and xlears it with a final speed of 45.0m/s. How much time is needed for the plane to clear the intersection.
52
MechanI seem to get different answers from this for this question. A small car travelling at a constant speed of 20ms-1 on a horizontal road is subjected to air resistance of 570N and road friction of 150N. a) What power providded by the engine of the car is used to keep it in motion at this speed? b) If the effieciency of the cars engine is 25%, at what rate is the chemical energy in the fuel being transformed? c) If 1 Litre of fuel provides 3.3 107 J of chemical energy when it is burned, how much fuel is used by the car if it travels at this speed for 100km?
53
Mechanwhat is acceleraton
54
MechanA plane, travelling at 800 m/s and 1000 m above the earth, drops a bomb weighing 500 kg. How long (in seconds) will it take the bomb to strke the earth and how far (in meters) will the bomb travel before striking the earth?
55
MechanDo things of different weight fall at the same speed when dropped from the same height? Will they fall at the same time on the ground?
56
Mechanwhy when a 15cm chalk dropped horizontally to the floor will break into 3 parts?
57
MechanA block is put on a horizontal table with which it has a coefiicient of friction of 0.25. While on theis table the block is pushed up against a spring such that the spring is compressed and the block is stationary. The block is now released and it slides 60 cm across the table before coming to a stop. Now the same experiment is repeated except that the spring is compressed twice as much as before. What is the distance the block slides across the table in this new case?
58
MechanI am most obliged if someone can clear my doubts on pulley system: 1. Why is a movable pulley more efficient than a fixed pulley? 2. What governs the efficiency of a movable pulley system?
59
MechanA 3.00-g sample of an unknown type of radioactive material has decreased after two days to the point that 2.52g remain. (a) What is the half life of this material?
60
Mechan30. An oar is held by a rower at .35m from the oarlock. The oar makes contact with the water at an average of 1.3 m from the oarlock. If the force applied by the rower on the oar is 80N. what is: a)the force of the oar on the water, and b)the force on the oarlock the anwers are a) 22N and b) 100N I need to know the method to getting the answer correct!!!
61
Mechanit's not a textbook problem. just been driving me up the wall. two cars, drivng towards each other (1-d). 25 m/s and 35 m/s respectively. cars are 225m apart and hit the brakes, both decelerating at 4.0 m/s^2 ... when do they collide and what's their relative velocities on impact?
62
MechanA falling stone takes 0.30s to pass a window which measures 2.1m top to bottom. From what height did the stone fall?
131
MechanA sign on a rectangular board is 62 cm wide, 29cm high and has a mass of 9kg. The board can swing on an axle through the upper left hand corner, but it is held in position by a rope attached to the upper right hand corner. IF the rope leans to the left, making, forming an angle of 60 degrees with the vertical. What will be its tension? If the rope breaks allowing to the sign to swing down, what will be its initial angular acceleration? Hint: Use the parallel axis theorem to find the moment of inertia.
137
MechanA 2kg block is released with an initial speed of 5 m/s along a horizontal tabletop toward a light spring with force constant 10 N/m. The coefficient of Kinetic friction between block and table is 0.25, and the block is initially 2.0 m from the spring. a) What is the max compression of spring? b) How far from the spring is the block when it comes to rest?
139
Mechan Lets say a guy is hanging still from a single vertical rope. He starts to climb upwards. I understand that the tension upwards is initially equal to the downward force mg so that the guy is stationary. But how is it that he is able to pull himself upwards with a velocity that he initiated into the system without there being a net positive force upwards? I can calculate the problems by using newtons laws and plugging stuff in, but conceptually it seems strange to me. Please help. s=distance The confusion started when I had to work several power problems of this climbing rope type where P=W/T= ma(s)/T where we must assume a=9.8
140
MechanA double atwood's machine has mass one on pulley one an
141
MechanA 10 Kg crate is pulled up a rough incline with an initial speed of 1.5 m/s. The pulling force is 100 N parallel to the incline, which makes an angle of 20 degrees with the horizontal. If the coefficient of kinetic friction is .4 and the crate is pulled a distance of 5 meters. a) what is the change in kinetic energy of the crate? b) what is the speed of the crate after it is pulled 5 meters? The text says the answer for a) is 150 Joules and for b)5.6 m/s. The wierd thing is that when I calculated these questions excluding friction those are the answers I got. When I formulated an equation including friction I got smaller numbers. Please help, I'm taking this independant study and have to figure everything out alone.Thanks.
142
MechanA mass, M, starts from rest and slides down the frictio
147
MechanFrictionless pulley? What bout the tension on the rope?
148
MechanA helicoptor rotor blade can be considered a long thin rod, If each of the three rotor blades is 3.37 m long and has a mass of of 160 kg, calculate the moment of inertia of the three rotor blades about the axis of rotation. How much torque must the motor apply to bring the blade up to a speed of 5.o rev/s in 8.0 s/
151
MechanA ball is thrown straight upward and rises to a maximum height of 16 m above its launch point. At what height above its launch point has the speed of the ball decreased to one-half its initial value?
167
MechanA 30 g ice cube at its melting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporization of 200 kJ/kg? Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.
172
MechanThe question I have is conceptual. Am I correct in assuming that if a solid object equally as dense as water is placed gently on the surface of the water water it will sink until it is slightly below the surface of the water and then be at equilibrium whereas an object that is less dense will just float. Moreover, if the object is slightly MORE dense will it accelerate downward even if it is ONLY slightly more dense than the water?
173
MechanA 3.0-kg particle has a velocity of (3.0i-4.0j) m/s. Find its x and y components of momentum and the magnitude of its total momentum.
174
MechanA 7.00 kg bolwing ball moves in a straight line at 3.00 m/s. How fast must a 2.45g Ping Pong ball move in a straight line so that the two balls have the same momentum?
175
Mechan A child bounces a superball on the side walk. The linear impulse delivered by the sidewlak to the ball is 2.00N.s during the 1/800 s of contact. What is the magnitude of the average force exerted on the ball by the sidewalk?
176
MechanA superball with the mass of 60g is dropped from a height of 2.0m. It rebounds to a height of 1.8 m. What is the change in its linear momentum during the collision with the floor?
177
MechanThe force Fx acting on a 2.0kg particle varies in time
178
MechanIn a slow pitch softball game, a 0.200kg softball
180
MechanA garden hose is held in the manner shown in Figure P9.
182
Mechan(a) if the momentum of an object is doubled in magnitud
183
MechanA 50kg football is thrown with the speed of 15 m/s. A s
184
MechanA car is stopped for a traffic signal. When the light turns green, the car accelerates, increasing in speed from zero to 5.20 m/s in 0.832 s. What is the linear impulse and average force dose a 70 kg. passanger in the car experience?
185
MechanWater falls without splashing at a rate of 0.25 liter/s from a height of 60 m into a 0.75 kg bucket on a scale. If the bucket id originally empty, what does the scale read after 3.0s?
192
MechanA potter's wheel, a thick stone disk of radius 0.50m an
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MechanA uniform solid sphere of radius r is placed on the ins
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MechanA uniform rod of weight w and length L is supported at
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MechanA vaulter holds a 29.4-N pole in equilibrium by exertin
196
MechanA pendulum of length 1.00 m is is released from an ini
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MechanConsider an undamped forced oscillator at resonance so
199
MechanA solid sphere (radius =R) rolls without slipping in a
200
MechanA 2.00 kg block hangs without vibrating at the end of a
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Mechanhelp
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MechanShow that is a torsional pendulum is twisted through an
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MechanThe mass of the deuterium molecule (D2) is twice that o
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MechanA mass m1= 9.0 kg is in equalibrium while connected to
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MechanA long thin rod of mass M and length L oscillates about
207
MechanConsider a damper oscillatior as illustrated in Figure
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MechanA horizontal plank of mass m and lenghtL is pivoted at
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MechanA horizontal platform vibrates with simple harmonic mot
210
MechanA block rests on a flat plate that executes vertical si
211
MechanA large passanger of mass 150kg sits in the car of Prob
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MechanA weight of 40.0 N is suspended from a spring that has
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MechanCalculate the resonant requencies of (a) 3.00kg mass at
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MechanA 2.00kg mass atached to a spring is driven by an exter
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MechanA pedulum of length 1.00m is released froman inital ang
216
MechanShow that the time rate of change of mechanical energy
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MechanConsider the specified single piston engine in Figure P
218
MechanWhile riding behind a car traveling at 3.o m/s you moti
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MechanA clock balance wheel has a period of oscillation of 0.
220
MechanA simple pendulum has a lenght of 3.00m. Determine that
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MechanA simple pendulum has a lenght of 3.00m. Determine that
222
MechanConsider the physical pendulum of Figure 13.11 (a) If i
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MechanA mass is attached to the end of a string to form a sin
224
MechanA meter stick, suspended at one end by a 0.50m long lig
225
MechanA simple pendulum has a period of 2.50s (a) what is its
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MechanA 2.00kg mass is attached to a spring and placed on a h
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MechanThe amplitude of a system moving in simple harmonic mot
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MechanA bullet of mass 10.0g is fired into and embeds in a 2.
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MechanA particle that hangs from a spring oscillated with an
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MechanA 1.0 KG MASS IS ATACHED TO A HORIZONTAL SPRING THE SPR
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MechanA piston `in an autommobile engine is in simple harmoni
236
MechanDescribe the working of a color television set.
256
MechanDear tutor: This is a question from the Oxford University entrance exam 1987: A car of mass 'm' moves without friction on a circular track in a vertical planes so that the centre of mass of the car is deistance 'r' from the centre of the circle. The car moves under gravity and the speed 'v' at the base of the track is just sufficient to allow a complete circuit without leaving the track. Obtain an expression for 'v' involoving the radius 'r' and the acceration due to gravity, 'g'. the solution that I got (which I think is wrong) is that the kinetic energy lose from the bottom of the circle is equal to the potential energy gain at the top of the circle. so iin thsi case: 1/2mv*2 = mgh (where h is 2r) then I can find v, BUT, I think this is wrong because this also means that the potential energy lose from the top of the circle is equal to the kinetic energy gain by the car when it reaches the bottom again, which means the car will carry on move around the circle as the track has no friction. Can you tell me what is wrong with my idea and guide me to the right idea? Thank you very much for all your help, I hope I can hear from you as soon as possible.
257
MechanA pebble is dropped into a well and 3 s later a splash is heard. The speed of sound in air is 340 m/s. How long does it take for the pebble to hit the water? How long does it take for the sound to reach the human What is the depth of the well??
267
MechanNote: the book is available in PS or PDF here: http://hw.serv.ph.utexas.edu/books Cubic Velocity Relationship The velocity of a particle moving along the x axis is given by v(sub x) = for t > 0, where a = 32m/s^2, b = 2m/s^4, and t is in s. What is the acceleration of a(sub x) of the particle when (after t = 0) it achieves its maximum displacement in the positive x direction?
275
MechanvENUS IS AN AVERGE DISTANCE OF 1.08 TIMES 10 TO THE 8KM FROM THE SUN. ESTIMATE THE LENGTH OF THE VENUSIAN YEAR USING THE FACT THAT THE EARTH IS 1.50 TIMES 10 TO THE 8KM FROM THE SUN ON THE AVERAGE.
276
MechanIn the 100 meter dash a sprinter accelerates from rest to a top speed with an acceleration whose magnitude is 2.68 m/s squared. After achieving top speed, he runs the remainder of the race without speeding up or slowing down. If the total race is run in 12.0 seconds, how far does he run during the acceleration phase?
286
MechanA rifle is aimed horizantely at a target 100ft away. The bullet hits the target .75 inches below the aiming point. (a)what is the bullets time of flight? (b)what was the muzzle velocity?
287
MechanTwo soccer players start from rest, 48m apart. They run
288
MechanOn a dry road a car with good tires may be able to brak
292
Mechanwhy is a massive cleaver more effective for chopping vegetables than an equally sharp knife?
293
MechanThe chimney of a stationary toy train consists of a ver
294
MechanIf my weight is 127lbs. What is my mass in kilograms? A
295
MechanDoes a 2-kg iron brick have twice as much inertia as a
301
MechanA ball which is thrown vertically upward reaches a particular height after a time t(1) on the way up and a time t(2) on the way down. Prove that a) the initial velocity with which the ball was thrown has a magnitude o.5g(t(1)+t(2)) and b) height H=.5gt(1)t(2). t(1)=time 1, and t(2)= time 2.
302
Mechan From fundamental physical constants (including
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MechanMr Physics Person I've been working on this problem and i just dont get it. ok you have....Now imagine that there is a weight on the right side and the left is attatched to the wall. Is the weight on the left going to be 2 times the tension on the right or just the tension on the right to balance the weight? Agggggghhhhh help!!!
307
MechanWhen a droplet of oil spreads out on a smooth water surface, the resulting "oil slick" is approximately one molecule thick. An oil droplet of mass 9.00*10^(-7) kg and density 918 kg/m^3 spreads out into a circle of radius 41.8 cm on the water surface. What is the diameter of an oil molecule?
308
MechanA speedy tortois can run at 10.0 cm/s, and a hare can r
309
MechanThe new BMW M3 can accelerate from zero 50 60 mi/h in 5
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MechanThe minimum distance required to stop a car moving at 3
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MechanA roller coaster moves 200 ft horizontally, then travel
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MechanA teenager has a car that accelerates at 3.0 m/s^2 and
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MechanSpeedy Sue driving at 30 m/s enters a one-lane tunnel.
327
MechanA hot air balloon is travelling vertically upward at a
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MechanA stone falls from rest from the top of a high cliff.
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MechanAn airplane starting from airport A flies 300 km east,
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MechanIndiana Jones is trapped in a maze. To find his way ou
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MechanAnother scheme to catch the roadrunner has failed, and
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MechanDoes an object dropped out of a moving car take longer
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MechanAn engineering student wants to throw a ball out of a t
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MechanA motorist is traveling at 18.0 m/s when he sees a deer
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Mechan3. [HRW.2.8.87P] A hot-air balloon is ascending at the
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Mechan3. [HRW.2.8.87P] A hot-air balloon is ascending at the
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Mechan1. [HRW.3.2.3E] A person walks in the following pattern
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Mechan Radio signals travel at 3x108 m/s or 0.30 km/ms. Suppo
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Mechan1)Is it possible for an object to have zero velocity bu
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MechanMasses, pulleys, and a force, yet no numbers...
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MechanA rock, starting from rest and falling freely, falls th
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MechanA ball is thrown vertically upward with an initial spee
351
MechanHow many grams of copper are required to make a hollow
352
MechanAssuming that 70 percent of the Earth's surface is covered with water at an average depth of 1 mile, estimate the mass of the water on Earth in kilograms.
353
MechanThe diameter of our disk-shaped galaxy, the Milky Way, is about 1.0 x 10^5 lightyears. The distance to the galaxy nearest our own is about 2.0 million lightyears. If we represent the Milky Way by a dinner plate 25 cm. in diameter,determine the distance to the next dinner plate.
354
MechanHow do you begin to even start a problem like the fol
357
Mechana projectileis fired at an angle so that both the horiz
360
MechanA place kicker must kick a football from a point 36m fr
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Mechan Dear PhysicsTutor I'm doing a science project where
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Mechan1. The speedometer of an accelerating car is read as t
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Mechan1. Prove that for any object which is uniformly accerl
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MechanTwo aircraft are travelling in the same line in the same direction. At the instant that they are 2.0 km apart, the one which is in front is travelling at 200 km/h, and the one which is behind is travelling at 300 km/h. The lead plane has an acceleration of 2.0 km/h/s, and the second one an acceleratinon of 1.0 km/h/s. Calculate when the second one will be 1.0 km from the first one. answer: 4.7 x 10 s, or 1.5 x 10^2 s
365
MechanJust as a traffic light turns green, a waiting car star
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MechanA physicist finds that his car is stuck in the sand and
372
MechanA softball pitcher hurls a .250-kg ball around a vertic
373
MechanDaniel works for the circus part time on weekends. At a
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MechanI am in AP Physics C and am having some trouble with a
378
MechanThe pulleys in Fig. P4.8 are frictionless and have negl
379
MechanA student analyses an accelerating merry-go-round. A
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MechanA small block of mass m slides along the frictionless l
381
MechanFrom a bridge, one bullet is dropped while the other on
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MechanA space station in the form of a large wheel, 159 m in
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MechanYou are standing on the edge of a ravine that is 11.8 m
386
MechanAn athlete swings a 5.85kg ball horizontally on the end
392
MechanA cylinder lying horizontally in the corner of a room,t
393
Mechanin what ways are sound and light waves similar, or diff
394
MechanTwo bodies were thrown simultaneously from the same poi
396
MechanPeople say tides are caused by the moon's attraction.
405
MechanAddition of Vectors using components?
429
MechanOne stone is dropped from the roof of a building. 2.00 seconds later, another stone is thrown down at an initial speed of 30.0 m/s, and it is observed that the two stones land at the same time. How long did it take the first stone to reach the grou
436
MechanI want to find an equation that can predict the path of a know mass with initial velocity (v), accelerated due the gravitational force by the sun. In other words, I want an equation of displacement as a function of time, with changing acceleration(due to gravitational force).
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