Question

Two balls are moving on the same smooth horizontal plane. Their velocity components along one edge of the square plane are $10\sqrt{3}m/s$ and $20m/s$ respectively. Their velocity components along a perpendicular edge are $30m/s$ and $20m/s$ respectively. Find the angle between their directions of motion.

• A. ${15}^{\circ }$
• B. ${30}^{\circ }$
• C. ${60}^{\circ }$
• D. ${45}^{\circ }$

Answer 1

The correct option is A ${15}^{\circ }$

$tan\alpha =\frac{30}{10\sqrt{3}}$

$\Rightarrow \alpha ={60}^{\circ }$

$tan\beta =\frac{20}{20}$

$\Rightarrow \beta ={45}^{\circ }$

$\Rightarrow \alpha -\beta ={15}^{\circ }$