Energy Use with questions 1 – 4. A 2.0 x 10 3kg racecar accelerates from 25 m/s to a speed of 55 m/s in 8.0 seconds.

1. What was the kinetic energy of the racecar before it accelerated? KE = J
2. What was the kinetic energy of the racecar after it accelerated? KE = J
3. How much work was done by the racecar in accelerating? W = J
4. Ignoring drag, how much power was developed by the racecar in accelerating?

Calculate the amount of heat produced when 18000 coulombs of charge is transferred in one hour through a potential difference of 50v

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.