Question

A pair of adult nitwits sit balanced on a teeter totter type device. One of them, whose mass is 54.2 kg, is 1.20 m from the point of balance. The other chowder-head is 2.25 m from the point of balance. What is the mass of the second person

Answer 1

Answer:

28.91 kg

Explanation:

Applying the principle of moment

Sum of clockwise moment = sum of anti clockwise moment

From the question

Weight of the first person×distance from the balance point = Weight of the second person×distance from the balance point

mgd = m'gd'.................. Equation 2

Where m = mass of the first person, m' = mass of the second person, d = distance from the balance point of the first person, d' = distance from the balance point of the second person, g = acceleration due to gravity

make m' the subject of the equation

m' = md/d'.................. Equation 2

Given: m = 54.2 kg, d = 1.2 m, d' = 2.25 m

Substitute into equation 2

m' = 54.2(1.2)/2.25

m' = 28.91 kg

Hence the mass of the second person = 28.91 kg

Answer 2

Answer:

The mass of the second person is 28.91 kg

Explanation:

Given;

mass of the first adult, m₁ = 54.2 kg

distance of the first adult from the point of balance, x = 1.20 m

mass of the second adult, = m₂

distance of the second adult from the point of balance, y = 2.25 m

Taking moment about the point of balance, we will have

m₁x = m₂y

54.2 x 1.2 = 2.25y

2.25y = 65.04

y = 65.04/2.25

y = 28.91 kg

Therefore, the mass of the second person is 28.91 kg