Question

a ball moving with momentum of 5kgm /sec strikes against a wall at an angle of 45 degree and is reflected at the same angle. Calculate the change in momentum​

Answer 1

Given :-

• P = 5kgm/s
• Θ = 45°

_____________________________________

From the figure given above, there is no change in perpendicular component and cancel each other.

The initial momentum along the x - axis,

$\bf\green{P = P \cos \: Θ }$

The final momentum along the x-axis,

$\bf\green{P{f}= - P \cosΘ}$

So, change in momentum

$\bf\green{∆ \: P = Pf - Pi } \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \bf\green{∆ \: P = - 2P \cosΘ} \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \bf\green{∆ \: P = - 2 \times 5 \times \cos45°} \\ \bf\green{∆ \: P = - 7.071kgm/s} \: \: \: \:$

Change in momentum is -7.071 kgm/s