Answered

A rock falls off a cliff and hits the ground after three seconds. What is its velocity right before it hits the ground?



9.8 m/s



0.31 m/s



29.4 m/s



3.3 m/s

Verified Answer :

mpanderla95

To solve this kinematics formula use the following equation:

Vf = Vi + at
Vf = 0 + (9.81 m/s^2)(3 seconds)
Vf = 29.43 m/s and or about 29.4 m/s of reported to 3 significant figures.

Erudite1

The correct answer is 29.4 m/s.

The right formula to use for the scenario given in the question is:

Vf = Vi + at

Where: Vf = Final velocity = ?

Vi = Initial velocity = 0

a = Acceleration [due to gravity] = 9.8 m/s

T = Time = 3 s

Note that an object that is falling down from a height has an initial velocity of zero.

Vf = 0 + [9.8 * 3] = 29.4

Therefore, final velocity = 29.4 m/s.

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