Question

In this fulcrum, the weights are perfectly balanced. How far must the fulcrum be located from the 60 pound weight if the bar is 24 feet long?

A) 9
B) 15
C) 12

Answer 1

15

Explanation:

Answer 2

15 feet

Explanation:

Given : In this fulcrum, the weights are perfectly balanced.

To Find: How far must the fulcrum be located from the 60 pound weight if the bar is 24 feet long?

Solution:

To make the weights perfectly balanced torque must be equal

`Torque = Force * d`

Where
`Force = Mass * Acceleration`

Let a be the acceleration

d= Distance between the pivot and the acting point.

Let x be the distance from 60 pound weight where fulcrum is located

Since we are given that Length of bar = 24 feet.

So,Distance of fulcrum from 100 pound weight = 24-x

Now torque for 60 pound weight :

`Torque = 60a * x`

Now torque for 100 pound weight.

`Torque =100a * (24-x)`

Now to maintain the equilibrium i.e. To make the weights perfectly balanced

`60a * x =100a * (24-x)`

`60x = 2400-100x`

`160x = 2400`

`x = (2400)/(160)`

`x = 15`

Hence The fulcrum must be located 15 feet from the 60 pound weight if the bar is 24 feet long.