Question

A bullet enters a block of wood with a velocity of 600 m/s and just penetrates to a depth of 0.2 m. Calculate the retardation.​

Answer 1

Answer:

v²=u²+2as

0=600²+2a×0.2

-2a×0.2=360000

-0.4a=360000

a=-360000/0.4

 =-900000 m/s²

Answer 2

Given :

➳ Initial velocity of bullet = 600m/s

➳ Final velocity of bullet = zero

➳ Distance = 0.2m

To Find :

⟶ Retardation of bullet.

Solution :

➨ Since, Retardation has said to be constant throughout the motion, we can easily apply equation of kinematics to solve this question.

➨ Third equation of kinematics :

$\bigstar\:\underline{\boxed{\bf{v^2-u^2=2as}}}$

• v denotes final velocity
• u denotes initial velocity
• a denotes acceleration
• s denotes distance

$\dashrightarrow\tt\:v^2-u^2=2as\\ \\ \dashrightarrow\tt\:(0)^2-(600)^2=2a(0.2)\\ \\ \dashrightarrow\tt\:0-360000=0.4a\\ \\ \dashrightarrow\tt\:a=-\dfrac{360000}{0.4}\\ \\ \dashrightarrow\underline{\boxed{\bf{a=-900,000\:ms^{-2}}}}$

[Note : -ve sign of a shows retardation.]