$A$ body whose momentum is constant must have constant

$A$ body of mass $2 \, kg$ collides with a wall with a speed of $100 \, m/s$ and rebounds with the same speed. If the time of contact was $1/50 \, s$,the force exerted on the wall is:

The dimensions of impulse are equal to that of

Using the variation of force and time given below, the final velocity of a particle of mass $2 \, kg$ moving with an initial velocity $6 \, m/s$ will be: (in $m/s$)

The resultant of action and reaction is zero. (True or False)

$A$ particle of mass $m \, kg$ moving with a velocity $v \, m/s$ strikes a surface as shown in the figure and rebounds with the same speed. The magnitude of the change in momentum is: