using second law of motion derive the relation between force and acceleration . a bullet of 10g strike a sand bag at a speed of 1000m/s and gets embeded after travelling 5 cm .calculate

(1)the resistive force exerted by sand on bullet

(2)the time taken by the bullet to come to rest

we have

v² - u² = 2as

or

acceleration

a = (v² - u²) / 2s

here,

u = 1000m/s

v = 0

s = 5cm = 0.05m

so,

a = (0 - 1000²) / (2x0.05)

thus,

a = -10000000 m/s²

and the retarding force will be

F = ma

here,

m = 10g = 0.01kg

so,

F = 0.01 x 10000000

thus,

F = 100000N

..

time taken will be

t = (v - u) / a

or

t = (0 - 1000) / -10000000

thus,

t = 0.0001s