Question

A weightlifter lifts a 13.0-kg barbel from the ground an moves it a distance of 1.3 meters. What is the work se does on the barbell?

Answer 1

The work done on the barbell is -165.62 Nm.

Explanation:

Work done on any object is the measure of force required to move that object from one position to another. So it is determined by the product of force acting on the object with the displacement of the object.

In the present problem, the displacement of the object on acting of force is given as 1.3 m. And the weight of the object which is a barbel is given as 13 kg. As the work is to lift the object from the ground, so the acceleration due to gravity will be acting on the object. In other words, the force applied on the object to lift it should be in opposite direction to the acting of acceleration due to gravity.

Thus, $Force = - Mass * Acceleration due to gravity = - 13 * 9.8 =-127.4 N$

Now, the force is -127.4 N and the displacement is 1.3 m.

So, $Work done = F*d$

$Work done = -127.4* 1.3 = -165.62 Nm$

So, the work done on the barbell is -165.62 Nm.