Question

A 39-kg girl is bouncing on a trampoline. During a certain interval after leaving the surface of the trampoline her kinetic energy decreases to 160 J from 490 J. How high does she rise during this interval? Neglect air resistance.

Answer 1

Answer:

The distance is 0.86 m.

Explanation:

Given that,

Mass = 39 kg

Initial kinetic energy, $K.E_{i} = 160\ J$

Final kinetic energy, $K.E_{f} = 490\ J$

We need to calculate the work done

According to work energy theorem

$W = \Delta K.E$

$W=K.E_{f}-K.E_{i}$...(I)

Work done is the product of the force and displacement.

$W = mgh$....(II)

From equation (I) and (II)

$K.E_{f}-K.E_{i}=mgh$

$490-160=39\times9.8\times h$

$h = 0.86\ m$

Hence, The distance is 0.86 m.