Question

A bullet of mass \(200 g\) having initial kinetic energy \(90 J\) is shot inside a long swimming pool as shown in the figure. If it’s kinetic energy reduces to \(40 J\) within \(1 s\), the minimum length of the pool, the bullet has to travel so that it completely comes to rest is

• A. 45 m
• B. 90 m
• C. 125 m
• D. 25 m

Answer 1

The Correct Option is A

u = \(\frac{1}{0.2}\) \(\sqrt{2×0.2×90}\) = 30 \(m/s\)

v = \(\frac{1}{0.2}\) \(\sqrt{2×0.2×40}\) = 20 \(m/s\)

a=\(\frac{20-30}{1}\) = -10 \(m/s^2\)

s = -\(u^2/2a\) = 45 \(m\)