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Question · Revise, Reflect, Refine, Q12, page 113
A bullet of mass 50 g moving with a speed of 100 m s⁻¹ enters a heavy stationary wooden block and stops after penetrating a distance of 50 cm. Estimate the stopping force acting on the bullet (assume that the bullet undergoes constant acceleration within the block).
![Question 12 — A bullet of mass 5 - How Forces Affect Moti - [Teachoo] - Questions at the end of the chapter](https://cdn.teachoo.com/3d2d2118-e62f-4d6a-91a3-0c405070acc2/animation-for-a-bullet-of-mass-50-g-moving-with-a-speed-of-100-m-s-enters-a-heavy-stationary-wooden-block-and-stops-a.gif)
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Answer
- Given: m = 50 g = 0.05 kg, u = 100 m s⁻¹, v = 0 m s⁻¹, s = 50 cm = 0.5 m
- Using v² = u² + 2as, 0 = (100)² + 2 × a × 0.5
- a = −10000 m s⁻²
- Force, F = ma = 0.05 kg × (−10000 m s⁻²) = −500 N
- Answer: The stopping force is 500 N, acting opposite to the direction of motion of the bullet.
