A ball rolls over the edge of a platform with only a horizontal velocity.The height of the platform is 1.6 m and the horizontal range of the ball from the base of the platform is 20 m.What is the horizontal velocity of the ball just before it touches the ground? Neglect air resistance.
A)35 m/s
B)9.8 m/s
C)20 m/s
D)4.9 m/s
E)70 m/s

Question

Quizplus · Accepted Answer

The horizontal velocity of the ball is constant throughout its flight. The vertical velocity of the ball is zero at the start of its flight and increases as it falls. The horizontal range of the ball is equal to the horizontal velocity multiplied by the time of flight. The time of flight can be found using the equation:$$t = \sqrt{\frac{2h}{g}}$$where h is the height of the platform and g is the acceleration due to gravity.The horizontal velocity of the ball can then be found using the equation:$$v = \frac{d}{t}$$where d is the horizontal range of the ball.Plugging in the given values, we get:$$v = \frac{20 m}{\sqrt{\frac{2(1.6 m)}{9.8 m/s^2}}} = 35 m/s$$

A Ball Rolls Over the Edge of a Platform with Only