Question

A bullet of mass 10 g with speed 90 km/h hit a sand bag and entered 2 m into the
bag. Find out the time it takes to stop and its retardation force.

Answer 1

Given:

A bullet of mass 10 g with speed 90 km/h hit a sand bag and entered 2 m into the  bag.

To find:

Find out the time it takes to stop and its retardation force.

Solution:

From given, we have,

A bullet of mass 10 g with speed 90 km/h hit a sand bag and entered 2 m into the  bag.

u = 90 km/hr = 25 m/s

we use the formulae,

v² = u² + 2as

0 = 25² + 2 × a × 2

0 = 625 + 4a

a = -156.25 m/s²

v = u + at

0 = 25 - 156.25 × t

t = 25/156.25

t = 0.16 s

F = ma

F = 10 × (-156.25)

F = -1562.5 N

Therefore, the time it takes to stop is 0.16 sand its retardation force is 1562.5N.