Question

A weight lifter is trying to lift a 1500-N weight but can apply a force of only 1200 N on the weight. One of his friends helps him lift it all the way. What force was applied to the weight by the weight lifter's friend?

Answer 1

300 N

Step-by-step explanation:

We have three forces acting on the object:

- W = 1500 N, downward: the weight of the object

- F1 = 1200 N, upward: the force exerted by the first man

- F2, upward: the force exerted by the friend

In order to lift the object, the sum of the two forces F1 and F2 must be at least equal to the weight of the object W. Therefore we can write

`F_1 +F_2 = W`

And from this equation, we can find the magnitude of F2:

`F_2 = W-F_1 = 1500 N-1200 N=300 N`