AS-LEVEL: Work, Energy & Power (PMT AQA pre-2016) Flashcards
State and explain how the horizontal forward force on the vehicle has to change for constant acceleration to be maintained from 0 to 27.8 m s–1
(3 marks)
-forward force would have to increase
-as speed increases, air resistance increases
-forward force must be greater than resistive drag force
- ∴ resultant force stays the same ∴ constant acceleration
A firework rocket is fired vertically into the air and explodes at its highest point. What are the changes to the total kinetic energy of the rocket and the total momentum of the rocket as
a result of the explosion? (1)
total kinetic energy of rocket, total momentum of rocket
A) unchanged, unchanged
B) unchanged, increased
C) increased, unchanged
D) increased, increased
C
The wooden block is replaced by a steel block of the same mass.
The experiment is repeated with the steel block and an identical pellet. The pellet rebounds after striking the block.
Discuss how the height the steel block reaches compares with the height of 0.63 m reached by the wooden block.
In your answer compare the energy and momentum
changes that occur in the two experiments.
(4 marks)
-as pellet rebounds, Δp of pellet is greater, ∴ Δp of block is greater
- ∴ initial speed of block is greater
- ∴ initial KE of block is greater
- ∴ height reached by steel block > height reached by wooden block
