Question

The force constant of a spring gun is $50 \,N / m$. If a ball of $20 \,g$ be shoot by the gun, so that its spring is compressed by $10 \,cm$, the velocity of the ball is:

• A. 5 m/s
• B. 15 m/s
• C. 25 m/s
• D. 20 m/s

Answer 1

Answer: (A)

5 m/s

Answer 2

$\frac{1}{2} mv ^{2}=\frac{1}{2} kx ^{2}$ $v =\sqrt{\frac{ R }{ m }} x$ $=\sqrt{\frac{50}{20 \times 10^{-3}}}\left(10 \times 10^{-2}\right)$ $=50 \times 10^{-1}$ $=5 \,m / s$