Ambiguity in part B -- Rocket engine failure...

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  • #1
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Question: A 7750 kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.35 m/s^2 and feels no appreciable air resistance. When it has reached a height of 555 m , its engines suddenly fail so that the only force acting on it is now gravity.

Part B: How much time after engine failure will elapse before the rocket comes crashing down to the launch pad?

So, I understood Part B to mean: calculate the time from 555 m, when the engines fail, to the max height, when velocity=0. However, they are looking for the time from when the engines shuts off, 555 m, to when it crashes.

I feel like Part B is ambiguous... we use MasteringPhysics and the book is great, but it seems like it was written in a lazy way. Maybe it's just me.

What do you think?
 

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  • #2
25
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Question: A 7750 kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.35 m/s^2 and feels no appreciable air resistance. When it has reached a height of 555 m , its engines suddenly fail so that the only force acting on it is now gravity.

Part B: How much time after engine failure will elapse before the rocket comes crashing down to the launch pad?

So, I understood Part B to mean: calculate the time from 555 m, when the engines fail, to the max height, when velocity=0. However, they are looking for the time from when the engines shuts off, 555 m, to when it crashes.

I feel like Part B is ambiguous... we use MasteringPhysics and the book is great, but it seems like it was written in a lazy way. Maybe it's just me.

What do you think?
p.s. I already solved the problem, but this wording is bothering me!
 
  • #3
haruspex
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p.s. I already solved the problem, but this wording is bothering me!
I agree it's unclear. Had it said "onto" the launch pad there would be no ambiguity.
 
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I agree it's unclear. Had it said "onto" the launch pad there would be no ambiguity.
Okay, thank you!
 

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