# Impulse

#### SengNee

A tennis ball of mass, m=0.060kg and a speed, v=28m/s strikes a wall at a 45 degree angle and rebound with the same speed at 45 degree as shown in the figure.
Calculate the impluse given by the wall.

#### topsquark

Forum Staff

A tennis ball of mass, m=0.060kg and a speed, v=28m/s strikes a wall at a 45 degree angle and rebound with the same speed at 45 degree as shown in the figure.
Calculate the impluse given by the wall.
You can calculate the impulse by calculating the change in momentum:
$$\displaystyle \overrightarrow{I} = \Delta \overrightarrow{p}$$

So define the +x direction to the right and the +y direction upward. The initial momentum components are
$$\displaystyle p_{0x} = mv~sin(45)$$
and
$$\displaystyle p_{0y} = mv~cos(45)$$

The final momentum components are
$$\displaystyle p_x = -mv~sin(45)$$
and
$$\displaystyle p_y = mv~cos(45)$$
(Remember the speed has not changed.)

So find the components of the change in momentum. They will be equal to the components of the impulse. So you can find the direction and magnitude of the impulse.

-Dan

SengNee