**Given that: **

m = 81gm = 0.081Kg, u = 300m/sec, s = 10cm = 0.1m, v = 0

As the force of resistance is acting in the opposite direction of motion of bullet, hence force of resistance will produce retardation on the bullet,

Apply, V^{2} = u^{2} – 2as

0 = 300^{2} – 2a(0.1)

a = 450000m/sec^{2}

Let F is the force of resistance offered by wood to the bullet.

Using equation, F = ma

F = 0.081 X 450000

**F = 36450N**

Let v = velocity of bullet with which the bullet emerges from the piece of wood of 5cm thick,

U = 300m/sec, a = 450000m/sec^{2}, s = 0.05m

Using equation, V^{2} = u^{2} – 2as

V^{2} = 300^{2} – 2 X 450000 X 0.05

**V = 212.132m/sec**