Initial velocity of the bullet, u = 150 ms⁻¹
Final velocity of the bullet, v = 0
Mass of the bullet, m = 10 g = 0.01 kg
Time taken by the bullet to come to rest, t = 0.03 s
Let distance of penetration be s
v = u + at
0 = 150 + a(0.03)
⇒ a = -5000 ms⁻² (- sign shows retardation)
v² = u² + 2as
0 = 150² + 2 × (-5000) × s
s = 2.25 m
Magnitude of the force exerted by the wooden block, |F| = m|a|
|F| = 0.01 × 5000 = 50 N