Question

A force acts on a 30 gm particle in such a way that the position of the particle as a function of time is given by x = 3t − 4t² + t³, where x is in metres and t is in seconds. The work done during the first 4 seconds is

Assertion: The change in kinetic energy of a particle is equal to the work done on it by the net force. Reason: Change in kinetic energy of particle is equal to the work done only in case of a system of one particle.

The graph between the resistive force F acting on a body and the distance covered by the body is shown in the figure. The mass of the body is 25 kg and initial velocity is 2 m/s. When the distance covered by the body is 4m, then what will be its kinetic energy?

A block of mass m is kept in an elevator which starts moving downward with an acceleration a₀ as shown in figure. The block is observed by two observers A and B for a time interval t₀.