# Physics

posted by Billie

A rocker acceleratess up ar 5m/s/s for 10s and at which point the fuel is exhusted, and then the rocket continues upwards in free fall.

a)How high does the rocket riseb)What total time does the rocket spend in the air?

b) What total time does the rocket spend in the air?

The rocket's acceleration is 5m/s^2 for 10s.
using s=(1/2)a*t^2 the distance it goes before it stops accelerating is
s=(1/2)5m/s^2*(10s)^2=250m.
At the 10s mark it velocity is give by
v=a*t=5m/s^2 * 10s = 50m/s
At that point the rocket has only velocity upward and is now being acted upon by gravity, so we use
(1) s=(-1/2)a*t^2 + v*t +y0
where v=50m/s and y0=250m
The rocket's velocity is given by
v=-g*t + v0
Where v0=50m/s. At the max height gt=v0 or t 50/9.8 s
Use that time in (1) to get the max height.
To figure the total time you should probably break up the path into parts.
The first 10s it accelerates. Then determine how long it takes to get from that point to the max height (you should've determined that above). Then determine how long it takes for the rocket to fall to the earth from that height under the influence of gravity from the equation in the first paragraph.

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