Question

a bullet moving with 10m/s hits a wooden plank bullet stops after penetrating plank 2 cm calculate retardation

Answer 1

u - initial velocity, v - final velocity, f - retardation, s - distance
v is 0 (because it has stopped)
u was 10m/s
s is 1 cm
applying the values
0=100-2.f. .01
f= 5000m/s^2 or 5000m/s square

Hope this helps!!