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

The distance is 0.86 m.

Step-by-step 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*9.8* h`

`h = 0.86\ m`

Hence, The distance is 0.86 m.