Question

Suppose an object’s initial velocity is 10 m/s and its final velocity is 4 m/s. Mass is constant.

Answer 1

The negative work done states that the work is done by the object and not on the object.

Explanation:

According to work energy theorem, the work done is equal to change in kinetic energy exhibited by the body. As the mass of the object is constant, and the velocity is decreased from 10 m/s to 4 m/s, the work done will be

           $W=\frac{1}{2} \times\left(u^{2}-v^{2}\right)$

Here W is the work done, m is the mass and v is the final and u is the initial velocity of the object. As the initial velocity is greater than the final velocity. So

          $W=\frac{1}{2} \times\left(4^{2}-10^{2}\right)=\frac{1}{2} \times(16-100)=\frac{1}{2} \times(-84)= - 42 J$

So the work done is negative for the given situation. The negative work done states that the work is done by the object and not on the object.