Two bodies of $5 \mathrm{kg}$ and $4 \mathrm{kg}$ are tied to a string as shown in the fig. If the table and pulley both are smooth, acceleration of $5 \mathrm{kg}$ body will be equal to-

Three forces start acting simultaneously on a particie moving with velocity $\overrightarrow{v}$ These forces are represented in magnitude and direction by the three sides of a triangle $ABC$ (as shown). The particle will now move with velocity

A ball weighing $10 \mathrm{g}$ hits a hard surface vertically with a speed of $5 \mathrm{m} {\mathrm{s}}^{-1}$ and rebounds with the same speed. the ball remains in contact with the surface for $0.01 \mathrm{s}$, then the average force exerted by the surface on the ball is :-