Question

Bullet moving with velocity of 200 m/s pierced 100 cm through a wooden block.what is its acceleration

Answer 1

Answer:

final velocity will be zero hence apply equation of motion

Answer 2

⇒Answer:

$\boxed{\bold{-20,000\;m/s^{2} }}$    

Explanation:

Given :

Initial Velocity, u = 200 m/s

Final Velocity, v = 0 m/s

Distance covered by object, S = 100 cm = 1m

To FIND:

Acceleration of the bullet = ?

SOLUTION :

According to Newton's Third equation of motion,

$\bold{v^{2} = u^{2} + 2aS }$

⇒$\bold{v^{2} - u^{2} = 2aS}$

⇒$\bold{0^{2} - 200^{2} = 2a\times 1}$

⇒$\bold{0 - 40000 = 2a}$

⇒$\bold{- 40,000 = 2a}$

⇒$\bold{ - 40,000}$ ÷ $\bold{2}$ $\bold{= a}$

⇒a = $\boxed{\bold{-20,000\;m/s^{2} }}$    

Hence the bullet experiences Retardation or Negative acceleration.

For Information :

To find the Time taken by the bullet for piercing through the wooden block

v = u + at

⇒v - u = at

⇒0 - 200 = -20,000 × t

⇒-200 ÷ -20,000 = t

⇒$\bold{\dfrac{-\not{200}}{-\not{20,000}} }$  = t

⇒$\bold{\dfrac{1}{100} } =$  t

⇒t = 0.01 s

Thus  the bullet takes 0.01 s for piercing through the wooden block