Newton’s Second Law Question; annoying

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Shadows_467
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#1
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The thrust generated by a rocket engine is equal to the mass of propellant burnt each second multiplied by the exhaust velocity of the gas. The Space Shuttle (with booster rockets and external tank) had a total mass of 2040000kg
at launch. In this question we shall assume that the exhaust velocity of the gas was 3000m/s.

How much propellant would have to be burnt each second in order for the spacecraft to accelerate upwards from the launch pad at "3𝑔
" (i.e. 30m/s2
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Joinedup
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(Original post by Shadows_467)
The thrust generated by a rocket engine is equal to the mass of propellant burnt each second multiplied by the exhaust velocity of the gas. The Space Shuttle (with booster rockets and external tank) had a total mass of 2040000kg
at launch. In this question we shall assume that the exhaust velocity of the gas was 3000m/s.

How much propellant would have to be burnt each second in order for the spacecraft to accelerate upwards from the launch pad at "3𝑔
" (i.e. 30m/s2
I think the catch is that it needs to burn it's engines hard enough to produce 1g worth of acceleration just to take the weight off it's mechanical supports and hover over the pad... the 3 g vertical acceleration is additional to that.
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Shadows_467
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Yh thx I worked it out. It was résultant force added to mass; 20400 + 6800:
27200
(Original post by Joinedup)
I think the catch is that it needs to burn it's engines hard enough to produce 1g worth of acceleration just to take the weight off it's mechanical supports and hover over the pad... the 3 g vertical acceleration is additional to that.
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jamiecress
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(Original post by Shadows_467)
The thrust generated by a rocket engine is equal to the mass of propellant burnt each second multiplied by the exhaust velocity of the gas. The Space Shuttle (with booster rockets and external tank) had a total mass of 2040000kg
at launch. In this question we shall assume that the exhaust velocity of the gas was 3000m/s.

How much propellant would have to be burnt each second in order for the spacecraft to accelerate upwards from the launch pad at "3𝑔
" (i.e. 30m/s2
I'm doing the same question but I'm stuck on the part before, could I get the answer to that question please?
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Shadows_467
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(Original post by jamiecress)
I'm doing the same question but I'm stuck on the part before, could I get the answer to that question please?
Yh probs done it now but 6800kg anyway; haven’t been on this forever
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Jonothan85743
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(Original post by Shadows_467)
Yh thx I worked it out. It was résultant force added to mass; 20400 + 6800:
27200
Could someone explain the reasoning for the entire question
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furlaflower
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sorry but how did it get to 6800, because for that question i did 2,040,000 kg divided by 3,000m/s and the answer that was given was 680....
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