CATAGORY: Mechanics QUESTION: Hi! 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?
Back to uncited catalog.
Back to uncited catalog.
Back to catalog.
Simplicity always works best. Keep that in mind when you are designing your egg cart. I thought that you might have the 1kg weight attached to a string which goes over a pully at the top of a 1meter high mast. The mast is attached to a cart which will be nothing more than a board with some wheels attached to it and a padded container for the egg. The string goes over the top of the pully at the top of the mast and then goes down the mast to another pully attached to the cart. The string then goes under the pully at the bottom of the cart and winds around a cylinder connected to one of the wheels. As the weight falls the string pulls on the cylinder creating a torque which will make the wheel turn and drive the cart forward. The string is wrapped around the cylinder but not attached to it. That way when the string runs out the cart will continue to move forward under its oun momentum otherwise the string will wind up again lifting the weight and slowing your car before it goes 6 meters. To get the car to stop how about having the weight hang off the back of the cart so that the weight hits the floor it leaves the cart. A second string however will be attached to the weight. The second string goes to a spool where enough string is attached so that the spool fully unwinds by the time the cart goes 6 meters. The the spool is attached to the cart so that the weight that was left behind acts like a boat anchor and this causes the cart to stop. I have never built such a device and there is always a gap between a design idea and its practical execution. Friction will be an important energy drain. Have VERY freely turning wheels and good pullys with bearings. Make the components small and light weight. use light weight wood like pine wood or balsa wood. You might have a tipping problem with the weight hanging off the back so make the cart long in the front like a drag racer car. Good luck! Let us know how you did! :-)