I need help, i tried this problem many times and i keep getting the wrong answer.(adsbygoogle = window.adsbygoogle || []).push({});

A test rocket is fired vertically upward from a well. A catapult gives it an initial speed of 79.2 m/s at ground level. Its engines then fire and it accelerates upward at 4.10 m/s2 until it reaches an altitude of 950 m. At that point its engines fail, and the rocket goes into free fall, with an acceleration of -9.80 m/s2. (You will need to consider the motion while the engine is operating separate from the free-fall motion.)

(a) How long is the rocket in motion above the ground?

___________s

(b) What is its maximum altitude?

_________km

(c) What is its velocity just before it collides with the Earth?

_________________m/s

I tried finding the time with the equations x=.5at^2+Vot+Xo. I get nowhere, please help. I plug in numbers and still get the wrong answer.

I tried doing different equations for going up, the time it stops in the air, and when it comes down, i just don't know which equation is right, though i do know you need three separate times to find the total time.

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# Homework Help: Test rocket acceleration physics problem

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