A hockey puck slides off the edge of a horizontal platform with an initial velocity of 20 m/s horizontally and experiences no significant air resistance.The height of the platform above the ground is 2.0 m.What is the magnitude of the vertical component of the velocity of the puck just before it hits the ground?
A)20 m/s
B)6.3 m/s
C)13 m/s
D)15 m/s
E)21 m/s

Question

Quizplus · Accepted Answer

The vertical component of the velocity is given by:$$v_{yf}^2 = v_{yi}^2 + 2g\Delta y$$where:* $v_{yf}$ is the final vertical velocity* $v_{yi}$ is the initial vertical velocity* $g$ is the acceleration due to gravity* $\Delta y$ is the change in heightIn this case, $v_{yi} = 0$, $\Delta y = -2.0 \ m$, and $g = 9.8 \ m/s^2$. Plugging these values into the equation, we get:$$v_{yf}^2 = 0 + 2(9.8 \ m/s^2)(-2.0 \ m) = -39.2 \ m^2/s^2$$Taking the square root of both sides, we get:$$v_{yf} = -6.3 \ m/s$$The negative sign indicates that the puck is moving downward.

A Hockey Puck Slides Off the Edge of a Horizontal