Question

If a stone of mass $0.05 \,kg$ is thrown out a window of a train moving at a constant speed of $100\, km/h$ then magnitude of the net force acting on the stone is

• A. 0.5 N
• B. zero
• C. 50 N
• D. 5 N

Answer 1

Answer: (A)

0.5 N

Answer 2

After the stone is thrown out of the moving train, the only force acting on it is the force of gravity i.e. its weight.
$\therefore F=m g=0.05 \times 10=0.5 \,N$.