JEE Mains · Physics · STD 11 - 5. work,energy,power and collision
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 1s, the minimum length of the pool, the bullet has a to travel so that it completely comes to rest is \(.....m\)
- A \(45\)
- B \(90\)
- C \(125\)
- D \(25\)
Answer & Solution
Correct Answer
(A) \(45\)
Step-by-step Solution
Detailed explanation
Using \(mv =\sqrt{2 mk }\) \(u =\frac{1}{0.2} \sqrt{2 \times 0.2 \times 90}=30\,m / s\) \(v =\frac{1}{0.2} \sqrt{2 \times 0.2 \times 40}=20\,m / s\) \(a =\frac{20-30}{1}=-10\,m / s ^{2}\) \(s =\frac{- u ^{2}}{2 a }=45\,m\)
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