Swimming is possible on account of

On a stationary sail-boat, air is blown at the sails from a fan attached to the boat. The boat will

A particle of mass $m$ is moving in a straight line with momentum $p$. Starting at time $t = 0$, a force $F = kt$ acts in the same direction on the moving particle during time interval $T$ so that its momentum changes from $p$ to $3p$. Here $k$ is a constant. The value of $T$ is

A $0.5\, kg$ ball moving with a speed of $12\,m/s$ strikes a hard wall at an angle of $30^o $ with the wall. It is reflected with the same speed at the same angle. If the ball is in contact with the wall for $0.25$ seconds, the average force acting on the wall is  ........... $N$

The time in which a force of $2 \,N$ produces a change of momentum of $0.4\,kg - m{s^{ - 1}}$ in the body is ......... $\sec$

Position-time graph for a particle of mass $100g$ is as shown in figure then impulse  acting on the particle at $t = 5$ second is ............ $N-s$