SOLUTION: An object is propelled vertically upward with an initial velocity of 20 meters per second. The distance s(in meters) of the object from the ground after t seconds is s = -4.9t^2 +

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Question 1207437: An object is propelled vertically upward with an initial velocity of 20 meters per second. The distance s(in meters) of the object from the ground after t seconds is s = -4.9t^2 + 20t.

(a) When will the object be 15 meters above the ground?

I think here I must let s = 15 and solve for t. Yes?

(b)When will it strike the ground?

I think here s = 0 and solving for t is needed. Yes?

(c)Will the object reach a height of 100 meters?

I think here s = 100 and I must solve for t.

Yes?
Answer by ikleyn(52775)   (Show Source):
You can put this solution on YOUR website!
.

(a) Yes. (b) Yes. (c) Yes. Try to solve this equation. If there is a real positive solution for time, then your answer to (c) is positive. If there is no real positive solution for time, then your answer to (c) is negative.

I answered all your questions.

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