What is linear momentum. Represent it in formula form. 

A rigid ball of mass $m$ strikes a rigid wall at $60^o $ and gets reflected without loss of speed as shown in the figure. The value of impulse imparted by the wall on the ball will be

In a carom-board game the striker and the coins are identical and of mass $m$ . In a particular hit the coin is hit when it is placed close to the edge of the board as shown in figure such that the coin travels  parallel to the edge. If the striker is moving with speed $v$ before the strike, then the net impulse on the striker during collision if it moves perpendicular to the edge after collision, is (assume all collisions to be perfectly elastic)

A ball is thrown up at an angle with the horizontal. Then, the total change of momentum by the instant it returns to the ground is

A girl riding a bicycle along a straight road with a speed of $5\,ms^{-1}$ throws a stone of mass $0.5\, kg$ which has a speed of $15\,ms^{-1}$ with respect to the ground along her direction of motion. The mass of the girl and bicycle is $ 50\, kg$. Does the speed of the bicycle change after the stone is thrown ? What is the change in speed, if so ?

$Assertion$ : A rocket moves forward by pushing the surrounding air backwards.

$Reason$ : It derives the necessary thrust to move forward according to Newton’s third law of motion