Question

A 450-N child is in a swing that is attached to a pair of ropes 1.80 m long. Find the gravitational potential energy of the child

Answer 1

Given:

weight of the child w = 450 N

mass of the child m = w/g

                                = 450/9.8

                                = 45.92 kg

length of the rope l = 1.80 m

(a)

gravitational potential energy when ropes are horizontal

U = mgh

    = 45.92*9.8*1.80

    = 810.02 J

(b)

when the child at 31⁰ angel with the vertical

U = mgl(1-cos?)

    = 45.92*9.8*1.80(1-cos31⁰)

    = 115.7 J

(c)

from the conservation of mechanical energy

at the bottom of the swing the child having kinetic energy only so the potential energy is zero.

Answer 2

betfom 2 57 93