# Answer to Question #5743 in Mechanics | Relativity for

Question #5743

A 38 kg child on a 1.4 m long swing is released

from rest when the swing supports make an

angle of 21.2 with the vertical.

The acceleration of gravity is 9.81 m/s2 .

a) What is the maximum potential energy

associated with the child?

Answer in units of J

from rest when the swing supports make an

angle of 21.2 with the vertical.

The acceleration of gravity is 9.81 m/s2 .

a) What is the maximum potential energy

associated with the child?

Answer in units of J

Expert's answer

Let's make following denominations:

α = 21.2°

L = 1.4 m

M = 38 kg

Now let's find the height a child moved up:

H = L*cosα = 1.4*cos(21.2) ≈ 1.3053 m.

So, the maximum potential energy of a child is

E = MgH = 38*9.81*1.3053 = 486.5723 J.

α = 21.2°

L = 1.4 m

M = 38 kg

Now let's find the height a child moved up:

H = L*cosα = 1.4*cos(21.2) ≈ 1.3053 m.

So, the maximum potential energy of a child is

E = MgH = 38*9.81*1.3053 = 486.5723 J.

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