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A stone is dropped from the top of a building 122.5 meters above the ground. Suppose the distance the stone travels from its starting point is described by s(t) = 4.9t², where t is in seconds. How fast is the stone traveling when it hits the ground?

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6 votes

Answer:

The speed of stone traveling when it hits the ground = 49 m/s

Step-by-step explanation:

Height of drop = 122.5 m

Given that distance the stone travels from its starting point

s(t) = 4.9t²

Substituting height

122.5 = 4.9t²

t² = 25

t = 5 seconds

So after 5 seconds stone hit the ground, we need to find velocity when t = 5 seconds.

Differentiating displacement with respect to time to get velocity,

s'(t) = 4.9 x 2 t = 9.8 t

Velocity when t = 5, s'(5) = 9.8 x 5 = 49 m/s

The speed of stone traveling when it hits the ground = 49 m/s

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