A bullet of mass 10g strikes a wooden block with velocity of 300m/s after penetrating 20cm into it, it's velocity drops to 200m/s. Then average resistance offered by the block is

V^2 = Vo^2 + 2a*d = 200^2.

300^2 + 2a*0.2 = 40,000,
0.4a = 40,000-90,000 = -50,000, a = -125,000 m/s^2.

F = M*a = 0.01 * (-125000) = -11250 N. Resisting the bullet.

Correction: F = -1250 N.

To find the average resistance offered by the wooden block, we can use the principle of conservation of momentum. The initial momentum of the bullet before impact is equal to its final momentum after impact.

The momentum of an object is given by the product of its mass and velocity. Therefore, the initial momentum of the bullet is:

Initial momentum = mass * initial velocity
= 0.01 kg * 300 m/s
= 3 kg·m/s

Similarly, the final momentum of the bullet is:

Final momentum = mass * final velocity
= 0.01 kg * 200 m/s
= 2 kg·m/s

The change in momentum of the bullet is the difference between the initial and final momenta:

Change in momentum = Final momentum - Initial momentum
= 2 kg·m/s - 3 kg·m/s
= -1 kg·m/s

The negative sign indicates that the direction of the bullet's momentum has changed.

According to the principle of conservation of momentum, the change in momentum of the bullet is equal to the impulse experienced by the bullet, which is equal to the average resistance offered by the wooden block multiplied by the time of collision.

Impulse = Change in momentum = Average resistance * Time of collision

Since the mass of the bullet and time of collision are not given, we do not have enough information to find the average resistance offered by the block.