Question

A bullet of 10 g strikes a sandbag at the speed of 10 power 3 metre per second and gets embedded after travelling 5 cm .calculate the resistive force exerted by the sand on the bullet and the time taken by the bullet to come to rest

Answer 1

Retardation experienced by bullet
a = u^2 / (2S)
= (10^3 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
= (10^3 m/s) / (10^7 m/s^2)
= 10^-4 seconds
= 100 microseconds

Answer 2

force = ma
=1/100x - 10000000=-100000N
t= 1/ 10000s