When some thing is stopped (or slowed), such as a bullet in a block of wood, a ball in mud a javilin in the ground, it is obviously slowed down to the point of stopping. This is commonly called deceleration (which is nothing more than negative acceleration)
This leads to a force, which is often referred to as Resistance, but governed by the same rules / conditions of Force , F = ma, and acceleration can be determined by one of the 3 equations of motion.
If a 75g bullet travels at 450 m/s and stops 1.1 m into a tree, calculate the resistance of the wood.
u = 450
v = 0
s = 1.1
a = ??
so calculate the deceleration (-ive acceleration) and from this calculate the force that the tree imparted on the bullet of mass, m .... because F = ma
Q5) A plane of mass 35T is landing. If it’s speed changes from 500 km/hr to 20 km/hr over 25 km, find
i) It’s deceleration
ii) The force needed to do this
iii) The net force acting on the plane?