The Student Room Group

Mechanics

A rocket is launched vertically up from the ground from rest with a constant acceleration of 5ms-2. After T seconds, it ceases to accelerate and travels with a constant velocity for 21 seconds, reaching a height of 1 km above the ground.

Draw a velocity-time graph for the vertical motion of the rocket for the time it takes to reach a height of 1km.
(2 Marks)

Find the value of T
(5 Marks)


At the point the rocket reaches 1km above the ground a panel becomes detached from the rocket and falls to the ground.

(i) Find the velocity the panel hits the ground
(ii) Select a modeling assumption you have used which limits the accuracy of your answer and justify why the answer would differ if this were taken into account. (4 Marks)
Reply 1
Original post by vaishnoraj
A rocket is launched vertically up from the ground from rest with a constant acceleration of 5ms-2. After T seconds, it ceases to accelerate and travels with a constant velocity for 21 seconds, reaching a height of 1 km above the ground.

Draw a velocity-time graph for the vertical motion of the rocket for the time it takes to reach a height of 1km.
(2 Marks)

Find the value of T
(5 Marks)


At the point the rocket reaches 1km above the ground a panel becomes detached from the rocket and falls to the ground.

(i) Find the velocity the panel hits the ground
(ii) Select a modeling assumption you have used which limits the accuracy of your answer and justify why the answer would differ if this were taken into account. (4 Marks)


What have you tried, which parts are you stuck with?
Reply 2
I am not able to solve anything.
Reply 3
Original post by vaishnoraj
I am not able to solve anything.

Have you covered this at school?
Reply 4
Yes. I have. But I do find Mechanics difficult at school too.
Reply 5
For the first part
https://www.bbc.co.uk/bitesize/guides/z2b9hv4/revision/4
Should help? Upload your attempt if you get stuck.
i also cannot do it
Reply 7
Original post by MetroBoomin11
i also cannot do it

This is an old thread, but have you tried following the link provided by the previous poster? It gives quite a clear explanation of what's going on.
Reply 8
Original post by davros
This is an old thread, but have you tried following the link provided by the previous poster? It gives quite a clear explanation of what's going on.

Ive Got the first part but not the rest of the questions.
Reply 9
Original post by dxvide
Ive Got the first part but not the rest of the questions.

Have you found T?
Original post by MetroBoomin11
i also cannot do it

So for part B
Use SUVAT

S=
U=0
V=?
A=5
T=T

Then using the formula v = u +at, so v =5t .
Then the distance equals area under the curve, so 1000 = (0.5*T*5T) +(5T * 21)
Then solve for T
Original post by vaishnoraj
Yes. I have. But I do find Mechanics difficult at school too.

Is this question from an international a level exam? if so which one?

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