Multi-Stage Rocket Problem
Unit: 1D Kinematics
Prerequisites
Later Topics
Multi-Step Problem Preview
Part 1 of 6 — sign up to solve the full problem!
Part 1
A model rocket is launched from rest from the ground. It accelerates upwards with a constant acceleration of for a time .
At , the thrusters stop firing and the rocket begins to accelerate downward under the influence of gravity, slowing until it reaches a peak, and then falls back to earth.
At what point is the speed of the rocket the greatest?
Correct!
The rocket has a speed of 0 at the start and when it reaches the peak height, so they cannot be the maximum.
The speed of the rocket when the thrusters stop firing is the maximum speed it will have on the way up - everything before that is slower, and after that point it slows down until it reaches peak height.
However, on the way down, the rocket will be going the same speed in the opposite direction when it reaches that some height. And then it continues to accelerate downwards, going faster and faster until it hits the ground.
Thus, the top speed is right before it hits the ground.
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