Question

Remember, there are far more marks for procedure than for final answers. Write your solutions neatly and in a well organized fashion. Show all work. All work submitted must be your own work. You are encouraged to work with other students but do not show each other the final work that you intend to submit. If you collaborate with other students it is a good idea to cite them as sources for your work. Questions to be handed in for marking 1. (very similar to several textbook questions) A 0.2 kg plastic cart and a 20 kg lead cart both roll without friction on a horizontal surface. (a) Equal forces are used to push both carts forward for a time of 1 s starting from rest. After 1 s is the kinetic energy of the plastic cart greater than, less than or equal to the kinetic energy of the lead cart? Explain. (b) Equal forces are used to push both carts forward for a distance of 1 m starting from rest. After 1 m is the kinetic energy of the plastic cart greater than, less than or equal to the kinetic energy of the lead cart? Explain. Note: You might think about how this question turns out differently if it is asked about the momentums of the two carts instead of their kinetic energies. But this is not part of the question and you don't have to answer it.

Answer 1

1) if the force acting on the two cars is same but the mass of the cars different

so kinetic energy K.E= 1/2 mV²

the plastic car gets more kinetic energy after 1 s because its mass is less than lead car (about 100 times )

2) Though the force acted on both the cars about 1 m ,

the the plastic car accelerates more than the lead car so

plastic car will have more kinetic energy than lead car