Homework Help: Physics

Posted by Leo on Tuesday, March 15, 2011 at 1:03am.

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.

Physics - drwls, Tuesday, March 15, 2011 at 7:06am
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.)

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