A block of mass `m` sits at rest on a frictionless table in a rail car that is moving with speed `v_(c)` along a straight horizontal track (fig.) A person riding in the car pushes on the block with a net horizontal force `F` for a time `t` in the direction of the car's motion.

What is the final speed of the block according to a person in the car ?

Options

A. `(Ft)/(m)`
B. `(2Ft)/(m)`
C. `-(Ft)/(m)`
D. zero

Answer

A

Explanation

`V = u + at = 0 + (Ft)/(m)`.