Question

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground?a. Its speed is the same as it was just as it was launchedb. Its horizontal velocity component is the same as it was just as it was launchedc. Its velocity is vertical.d. Its vertical velocity component is the same as it was just as it was launched.e. Its horizontal velocity component is zero.

Answer 1

Answer:

B) Its horizontal velocity component is the same as it was just as it was launched

Explanation:

From dynamic we know that free falling objects had two components of velocity

The only acceleration that takes place in this case is gravity in the y-component of velocity

$v_{vx}=v_{ox}+at\\v_{y}=v_{oy}+gt$

Since a=0 and $g=-9.8m/s^2=-32.2ft/s^2$ that means that the velocity at the y-component changes with time but the horizontal component remain the same

$v_{x}=v_{ox}$

This means that the horizontal velocity is not 0 but is the same as it was just as it was launched