A hammer of mass $500 \,g,$ moving at $50\, ms^{-1}$, strikes a nail. The nail stops the hammer in a very short time of $0.01\, s$. What is the force(in $N$) of the nail on the hammer?

Two objects of masses $100\, g$ and $200\, g$ are moving along the same line and direction with velocities of $2\, m\, s^{-1}$ and $1\, m\, s^{-1}$, respectively. They collide and after the collision, the first object moves at a velocity of $1.67\, m\, s^{-1}$. Determine the velocity(in $m/s$) of the second object.

If action is always equal to the reaction, explain how a horse can pull a cart.

From a rifle of mass $4\, kg$, a bullet of mass $50\, g$ is fired with an initial velocity of $35\, m\, s^{-1}$. Calculate the initial recoil velocity(in $m/s$) of the rifle.

According to the third law of motion when we push on an object, the object pushes back on us with an equal and opposite force. If the object is a massive truck parked along the roadside, it will probably not move. A student justifies this by answering that the two opposite and equal forces cancel each other. Comment on this logic and explain why the truck does not move.