Question

A bullet entered into a wooden block with a speed of 200m per second after traveling 400 cm it stopped calculate the retardation of the bullet

Answer 1

GiveN :

• Initial velocity (u) = 200 m/s
• Final velocity (v) = 0 m/s
• Distance travelled into wooden block before it stop (s) = 400 cm = 4 m

To FinD :

• Retardation of the bullet

SolutioN :

Use 3rd equation of motion :

$\dashrightarrow \boxed{\tt{v^2 \: - \: u^2 \: = \: 2as}} \\ \\ \dashrightarrow \tt{0^2 \: - \: 200^2 \: = \: 2 \: \times \: 4 \: \times \: a} \\ \\ \dashrightarrow \tt{-40000 \: = \: 8a} \\ \\ \dashrightarrow \tt{a \: = \: \dfrac{-40000}{8}} \\ \\ \dashrightarrow \tt{a \: = \: \dfrac{-40000}{8}} \\ \\ \dashrightarrow \tt{a \: = \: -5000} \\ \\ \underline{\sf{\therefore \: Retardation \: is \: - \: 5000 \: ms^{-2}}}$

Answer 2

Answer:

Given:

Speed of bullet = 200 m/s

Distance travelled before stopping = 400 cm

Final velocity = 0 m/s

To find:

Retardation of bullet

Concept:

Retardation refers to negative acceleration , in other words , acceleration in opposite direction as compared to Direction of velocity.

It is also known as Deceleration.

In this case, the frictional Force between the surface of bullet and the wooden blocks provides the Deceleration which stops the bullet.

Calculation:

Using Equations of Kinematics and assuming acceleration to be constant.

∴ v² = u² + 2as

=> (0)² = (200)² + 2 (a) (400/100)

=> 40000 = -2a (4)

=> a = - 40000/8

=> a = -5000 m/s²

So final answer :

$\boxed{ \red{ \huge{ \bold{acc = - 5000 \: m {s}^{ - 2} }}}}$