physics qs help please?

1st we need to determine the velocity and height after accelerating for 8 seconds. Use the following equation to determine the velocity.

vf = vi + a * t, vi = 0

vf = 49 * 8 = 392 m/s

Use the following equation to determine the height.

d = vi * t + ½ * a * t^2

d = ½ * 49 * 8^2 = 1,568 meters

As the rocket moves from this height to its maximum height, its velocity will decrease at the rate of 9.8 m/s each second. Use the following equation to determine the distance the rocket rises.

vf^2 = vi^2 + 2 * a * d, vf = 0, vi = 392, a = -9.8

0 = 392^2 + 2 * -9.8 * d

d = -392^2 ÷ -19.6 = 7,840 meters

Maximum height = 1,568 + 7,840 = 9,408 meters

OR

Use the following equation to time the rocket rises. vf = vi + a * t

0 = 392 – 9.8 * t

t = 392/9.8 = 40 seconds.

Use the following equation to determine the distance the rocket rises.

d = vi * t + ½ * a * t^2, vi = 392 m/s, a = -9.8, t = 40

d = 392 * 40 – ½ * 9.8 * 40^2 = 7840 meters

Since both answers are the same, I believe this answer was correct. If you need help in the future, make me one of your contacts. Your questions will come directly to my yahoo email address.

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Where v is end velocity, u is start velocity s is displacement (distance in set direction), t is time and a is acceleration.

t=8

a=49

u=0, since it is at rest

We want to find s and v

Firstly we need to find its height reached whilst there is still fuel

S=ut+0,5at^2

s=0+0.5*49*8*8

S=1568m

Then, at the point where fuel runs out we need to find its speed

V=u+a t

V= 0+49*8

V=392

After this point is is slowing down at a rate of 9.8m/s/s for this part of the journey:

A=-9.8

U=39.6

V=0 (at the point where it stops moving upwards it momentarily has zero velocity)

We want s

V^2=u^2+2as

0=39.6^2+2*-9.8*s

0=1568+-19.6s

19.6s=1568

S=80m

That shows once it runs out of fuel it continues to move 80m into the air

Total height =80+1568

=1648m

The highest point is 1648m above launch point

Just to make a point, these symbols are the proper symbols used by scientists and mathematicians, the equations used are called the kinematic a equations, or sometimes SUVAT, since they can be used to work out any of these five things from three others

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