question_answer 54)

                  A boy throws a ball in air at \[{{60}^{o}}\] to the horizontal along a road with a speed of 10 m/s (36 km/h). Another boy sitting in passing by car observes the ball. Sketch the motion of the ball as observed by the boy in the car, if car has a speed of (18 km/h). Give explanation to support your diagram.

Answer:

                  Horizontal component of the velocity of the ball                 \[u\,\,\cos 60{}^\circ =36\times \frac{1}{2}=18\text{ }km/h\]                 Vertical component of the velocity of the ball                 \[=u\text{ }\sin 60{}^\circ =36\times \frac{\sqrt{3}}{2}=\text{ }31.18\text{ }km/h\] Since the speed of car is equal to the horizontal component of the velocity of the ball, so for the boy sitting in the moving car, ball appears to move up vertically upward and then move down vertically downward.