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April 18, 2014

April 18, 2014

Posted by **Melinda** on Wednesday, March 14, 2012 at 6:19pm.

a) the height of the observation deck is 146.9 m. How fast is the object moving when it hits the ground?

The answer is 53.655 m/s.

Could someone explain how the book got 53.655 m/s.

- Calculus -
**Reiny**, Wednesday, March 14, 2012 at 8:05pmFirst you find the time it takes to hit the ground ...

4.9t^2 = 146.9

t^2 = 29.98 sec

t = √29.98 = 5.475

if d(t) = 4.9t^2

v(t) = 9.8t

v(5.475) = 9.8(5.475) = 53.659 m/s

Since you are in calculus, I am suprised that you did not know that the derivative of distance gives you velocity.

- Calculus -
**Reiny**, Wednesday, March 14, 2012 at 8:11pmFirst you find the time it takes to hit the ground ...

4.9t^2 = 146.9

t^2 = 29.98 sec

t = √29.98 = 5.475

if d(t) = 4.9t^2

v(t) = 9.8t

v(5.475) = 9.8(5.475) = 53.659 m/s

Since you are in calculus, I am suprised that you did not know that the derivative of distance gives you velocity.

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