A hockey puck slides off the edge of a platform with an initial velocity of 20 m/s horizontally.The height of the platform above the ground is 2.0 m.What is the magnitude of the velocity of the puck just before it touches the ground? You can neglect air.
A)21 m/s
B)22 m/s
C)24 m/s
D)25 m/s
E)6.3 m/s

Question

Quizplus · Accepted Answer

The magnitude of the velocity just before the puck touches the ground can be found using the Pythagorean theorem, combining the horizontal and vertical components of velocity. The horizontal velocity remains constant at 20 m/s because there is no horizontal acceleration. The vertical velocity can be found using the equation $v = \sqrt{2gh}$, where $g$ is the acceleration due to gravity (9.8 m/s$^2$) and $h$ is the height (2.0 m). This gives a vertical velocity of $\sqrt{2 \times 9.8 \times 2} = \sqrt{39.2} \approx 6.26$ m/s. The total velocity just before touching the ground is $\sqrt{20^2 + 6.26^2} \approx 20.78$ m/s, which rounds to 21 m/s.

A Hockey Puck Slides Off the Edge of a Platform