Question

A bullet of 10g strikes a sand bag at a speed of 103 m/s and gets embedded after travelling 5cm. Calculate(i) the resistive force exerted by the sand bag on the bullet.(ii) the time taken by the bullet to come to rest.

Answer 1

Retardation experienced by bullet
a = u^2 / (2S)
= (1000 m/s)^2 / (2 × 5 × 10^-2 m)
= 10^7 m/s^2

Resistive Force = ma
= 10 × 10^-3 kg × 10^7 m/s^2
= 100 000 N
= 100 kN

Time taken by bullet to come to rest
T = u / a
= (1000 m/s) / (10^7 m/s^2)
= 10^-4 seconds
= 100 microseconds

Answer 2

Answer:

Explanation:

Retardation experienced by bullet

a = u^2 / (2S)

= (1000 m/s)^2 / (2 × 5 × 10^-2 m)

= 10^7 m/s^2

Resistive Force = ma

= 10 × 10^-3 kg × 10^7 m/s^2

= 100 000 N

= 100 kN

Time taken by bullet to come to rest

T = u / a

= (1000 m/s) / (10^7 m/s^2)

= 10^-4 seconds

= 100 microseconds