High School

You are standing at the top of a high cliff. You drop a rock, and it hits the ground 4 seconds later. How fast was it going when it hit the ground?

A. -9.8 m/s
B. -38.2 m/s
C. -29.4 m/s
D. -19.6 m/s

Answer :

Answer:

B. -38.2 m/s

Explanation:

Given parameters:

Time of fall = 4s

Unknown:

Final velocity of the rock = ?

Solution:

To solve this problem, we use the expression below;

V = U + gt

V is the final velocity

U is the initial velocity

g is the acceleration due to gravity = 9.8m/s²

t is the time taken

Now, insert the parameters and solve;

V = 0 + (9.8 x 4) = 39.2m/s

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