Question

a bullet hits a wall with a velocity of 20 metre per second and penetrate it upto a distance of 5 cm. Find the negative acceleration on the bullet by the wall.

Answer 1

we will apply the 3rd equation of motion,

v² = u²+2as
u = 20m/s (initial velocity)
v = 0m/s (because the bullet comes to rest after penetration)
s = 5cm = 0.05m (distance travelled)

0² = 20²+2×a×0.05

-400= 0.1a

a = -4000m/s²

I hope you understand the approach.
All the best!

Answer 2

Answer:

4000 m/s ²

Explanation:

Initial velocity, u = 20 m/s  (Given)

Distance travelled, s = 5cm=0.05 m  (Given)

Let the retardation produced be = a  

The final velocity is v = 0.

Thus applying the third equation of motion -

= v² -u² = 2as

= 0 - (20)² = 2×0.05×a

= 0.1 a = - 400

= a = - 4000 m/s²

Thus the retardation/deceleration produced is 4000 m/s ².