Assertion: A quick collision between two bodies is more violent than a slow collision, even when the initial and the final velocities are identical.

Reason: Because the rate of change of momentum which determines the force is greater in the first case.

A person of mass $M \mathrm{kg}$ is standing on a lift. If the lift moves vertically upwards according to the given $v-t$ graph then find out the weight of man at the following instants: $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$ $t=1 \mathrm{second}$

A person of mass $M \mathrm{kg}$ is standing on a lift. If the lift moves vertically upwards according to the given $v-t$ graph, then find out the weight of man at the following instants: $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$, $t=8 \mathrm{second}$