Question

. A bullet of mass 50 g moving with an initial velocity
of 100 m s. strikes a wooden block and comes to
rest after penetrating a distance 2 cm in it.
Calculate : (i) initial momentum of the bullet,
(ii) final momentum of the bullet, (iii) retardation
caused by the wooden block, and (iv) resistive force
exerted by the wooden block
Ans. (i) 5 kg m s', (ii) zero,
(iii) 2,5 x 109 ms 2, (iv) 12500 N​

Answer 1

Answer:

Explanation:

Here, initial velocity, u = 100m/s

Final velocity, v = 0

Mass = (50/1000)kg = 0.05 kg

Distance traversed, S = 0.02 m

(i)Initial momentum, P' = mu = 0.05 x 100 = 5 kgm/s

(ii) final momentum, P'' = mv = 0.05 x 0 = 0

(iii)for calculating acceleration,

v^2 - u^2 = 2fS

0 - 10000 = 0.04f

f = -(10000/0.04) = -(10^6 / 4) = -2.5 x 10^ 5 m/s^2

Therefore retardation, a = -f = 2.5 x 10^5 m/s^2

(iv) resistive force, F = ma = 0.05 x 2.5 x 10^5

F = 1.25 x 10^ 4 = 12500N