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Home Q & A Board Science-Related Homework Help Mathematics
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mjcurry mjcurry
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8 years ago
If a stone is thrown vertically upward from the surface of the moon with a velocity of 5 m/s, its height (in meters) after t seconds is
h = 5t − 0.83t2.
(Round your answers to two decimal places.)
(a) What is the velocity of the stone after 3 s?
Incorrect: Your answer is incorrect. m/s

(b) What is the velocity of the stone after it has risen 5 m?
Incorrect: Your answer is incorrect. m/s
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#1
Staff Member
8 years ago
Similar Question
If a stone is thrown vertically upward from the surface of the moon with a velocity of 10 m/s, its height in meters after t seconds is h = 10t - 0.83t^2.

What is the velocity of the stone after it has risen 25 meters?

We can determine the time it takes to rise 25 meters as:

25 = 10t - 0.83t^2

-0.83t^2 + 10t - 25 = 0

0.83t^2 - 10t + 25 = 0

t = 3.54 or 8.51 seconds

Since we want the stone on the way up (not on the way down), we will use the 3.54 second figure.

dh/dt = 10 - (2)(0.83)t = 10 - 1.66t

Evaluating at t = 3.54 seconds gives

10 - 1.66(3.54) = 4.12 m/s Slight Smile
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