posted by Leo on .
1. It takes 190 kJ of work to accelerate a car from 21.0 m/s to 29.0 m/s. What is the car's mass?
2. A 32-kg girl is bouncing on a trampoline. During a certain interval after she leaves the surface of the trampoline, her kinetic energy decreases to 205 J from 435 J. How high does she rise during this interval? Neglect air resistance.
1. 190,000 = (M/2)(29^2 - 21^2)
Solve for M in kg
2. K.E. loss = P.E. gain
(425 - 235) = M g H
Solve for H, the distance she rises during that interval.
(She will rise still farther until her kinetic energy is zero.)