Topic : notions of work and kinetic energy : the work-energy theorem

A body possesses kinetic energy x, moving on a rough horizontal surface, is stopped in a distance y. The friction force exerted on the body is

The position $x$ of a particle of mass 2 kg moving along straight line is given as $x = (t-2)^2$, where $t$ is in second and $x$ is in metre. The work done by the force in first 2 s is

The kinetic energies of two similar cars A and B are 100 J and 225 J respectively. On applying breaks, car A stops after 1000 m and car B stops after 1500 m. If F_A and F_B are the forces applied by the breaks on cars A and B, respectively, then the ratio F_A/F_B is

A constant force is applied on a body of mass 4 kg to give it a displacement S = \frac{t^2}{2}. The work done by agent applying the force up to time t = 3 s is