Question

The kinetic energy of a body changes from 12 J to 60 J due to the action of a force of 5N on an object of mass 4 kg. The work done by the force is _____.

Answer 1

Hint: Work is the energy delivered to or from an item by applying force along a displacement in physics. It is frequently expressed as the product of force and displacement in its simplest form. When applied, a force is said to produce positive work if it has a component in the direction of the point of application's displacement. If a force has a component that is opposite the direction of displacement at the point of application, it produces negative work.
 $ \Delta W = {W_2} - {W_1} $ .

Complete answer:
The work done is given by: where the force F is constant and the angle between the forces is $ \theta $ and the displacement s is
 $ W = F\,s{\text{ cos}}\theta $
Because work is a scalar number, it only has magnitude and no direction. Work is the process of transferring energy from one location to another or from one form to another. The joule (J), which is the same unit as energy, is the SI unit of work.
Lifting twice the weight the same distance or lifting the same weight twice the distance doubles the labour. Work and energy are inextricably linked. According to the work–energy principle, an increase in the kinetic energy of a rigid body is generated by an equivalent amount of positive work done on the body by the force acting on it. A reduction in kinetic energy is generated by the resulting force doing an equivalent amount of negative work. As a result, if the net work is positive, the particle's kinetic energy increases by the same amount. If the total work done is negative, the particle's kinetic energy is reduced by the same amount.
 $ W = \Delta {E_K} $
From the question given
The kinetic energy of a body changes from 12 J to 60 J, so the work done can be easily mentioned as $ \Delta W = {W_2} - {W_1} $
Hence
 $ \Delta W = 60 - 12 $
 $ \Rightarrow \Delta W = 48J $ .

Note: The force and mass given In the question are additional information and have nothing to do with the problem of interest. Work on a free (no fields), rigid (no internal degrees of freedom) body is equal to the change in kinetic energy $ {E_k} $ corresponding to the linear and angular velocity of that body, according to Newton's second law.