Question

A bullet of mass 50 g moving with an initial velocity of $100m{s}^1$ strikes a wooden block and comes to rest after penetrating a distance of 2cm in it calculate
(i) initial momentum of a bullet
(ii) final momentum of the bullet
(iii) retardation caused by the wooden block and
(iv) resistive force exerted by the wooden block

Answer 1

Mass of the bullet is $m_b=50gm=0.05Kg$

Initial velocity of bullet $u_b=100m/s$

Final velocity is $v_b=0m/s$

(1) Initial momentum of bullet $p_i=m_b{u}_b=5Kgm/s$

(2) Final momentum of bullet $p_f=m_b{v}_b=0.05\times 0=0$

(3) Retardation occurred by the wooden block is

$v^2-u^2=2as$

$-{\left(100\right)}^2=2a\left(0.02\right)$

$a=-250000m/s^2$

(4) Resistive force

$F=ma$

$=0.05\times -250000$

$=12500N$