A bullet is shot vertically downwards with an initial velocity of 100 m s - 1 from a certain height. Within 10 s , the bullet reaches the ground and instantaneously comes to rest due to the perfectly inelastic collision. The velocity-time curve for total time t = 20 s will be : (Take g = 10 m s - 2 )

Step-by-step solution

As the upward direction is taken as positive, the velocity at t = 0 is u = - 100 m s - 1 . As it is falling under gravity, its acceleration is constant and a = - 10 m s - 2 . Applying equation of motion for constant acceleration during the time of fall i.e., for 0 to 10 s , v = u + a t ⇒ v = - 100 - 10 × 10 ⇒ v = - 200 m s - 1 After 10 s it hits the ground and remains at rest. Therefore, option A is the correct representation.