Question

A bullet moving with a velocity of 10 ms is brought to rest after penetrating a wooden plank of 4 cm thickness. The retardation of the bullet is [ ] al.1200 ms b)-1250 ms c) 1200 ms d) 1250 ms​

Answer 1

Appropriate Question:

A bullet moving with a velocity of 10 ms is brought to rest after penetrating a wooden plank of 4 cm thickness. The retardation of the bullet is :-

• (a) 1200 m/s²
• (b) -1250 m/s² ✔︎
• (c) 1200 m/s²
• (d) 1250 m/s²

Solution:

We know that,

➝ v² - u² = 2as

➝ v² = u² + 2as

➝ 0 = 10² + 2 × a × 0.04

➝ 0 = 100 + 2a × 0.04

➝ 0 = 100 + 0.08a

➝ -0.08a = 100

➝ a = -100/0.08

➝ a = -1250 m/s²

Hence, Retardation of bullet is -1250 m/s².