How High Does a Rocket Go If It Accelerates for 4 Seconds?

[bkoz316]

Finding Maximum Height?

A rocket moves striaght upward, starting from rest with an acceleration of 29.4m/s^2. It runs out of fuel at the end of 4.00seconds and continues to coast upward, reaching a maximum height before falling back to Earth.

(a.) Find the rocket's velocity and position at the end of 4.00seconds.

(b.) Find the maximum height the rocket reaches.






There was ten parts to this problem and I'm stuck on how todo these to.
Thanks sooo much for the help!

 

[dzogi]

a) $$s=\frac{1}{2}at^{2}; v=at$$
b) at the end of the 4 seconds period, the rocket will have velocity of $$v$$ (calculated above) and a downward negative acceleration of $$g=-9.81m/s^{2}$$. Do the rest yourself :)

Hint: You can also use the law of conversion of energy for the second part.