Acceleration

The final velocity after it passes the plank is .

Let be the thickness of the plank, the deceleration due to resistance of plank, is given by where is final velocity, is initial velocity, is acceleration and is displacement. Here Suppose the bullet is stopped after passing through such planks. Then the distance covered by bullet is .

The nature of path is decided by velocity, acceleration and its direction. Velocity is the ratio of displacement to time. It is a vector quantity possessing both magnitude and direction. When a particle's velocity changes, the particle is said to undergo acceleration. The instantaneous acceleration is the derivative of the velocity with respect to time. Acceleration is also a vector quantity, possessing both magnitude and direction. Depending on variation of velocity and acceleration, the path could be a straight line, circle or a parabola.