A train moves horizontally with constant speed 20 m/s. A passenger throws a ball vertically upward with speed 15 m/s relative to the train. Neglect air resistance and take g = 10 m/s². When the ball returns to the level of projection, its horizontal displacement relative to the ground is:
Options

Question

A train moves horizontally with constant speed 20 m/s. A passenger throws a ball vertically upward with speed 15 m/s relative to the train. Neglect air resistance and take g = 10 m/s². When the ball returns to the level of projection, its horizontal displacement relative to the ground is:

Options

G1 Physics · Accepted Answer

Relative to the ground, the ball has horizontal velocity 20 m/s and vertical initial velocity 15 m/s. Time of flight back to the same level is T = 2uᵧ/g = 30/10 = 3 s. Horizontal displacement = vₓT = 20×3 = 60 m. Therefore option C is correct.