If work is done on a body, the body will accelerate, change position or change shape. In the former case, the body gains kinetic energy.
If body A is moving, it can do work on body B through colliding.
The equation for Ek can be derived by considering the work done by a constant force. If the force is constant, the the acceleration is constant (since F=ma), so the suvat equations can be applied:
\(E_k ={1\over2}mv^2\)
Use quizzes to practise application of theory.
START QUIZ!
How much work is require to increase the velocity of a 2 kg mass from 1 ms-1 to 2 ms-1 .
Work = increase in KE = 1/2 m (v2 2- v12)
A 2 kg mass has a kinetic energy of 9 J.
It's velocity is:
1/2 mv2 = 9
v = √9
A 2 kg ball travelling at 4ms-1 loses 1/ 2 of its kinetic energy.
Its velocity is now
KE = 16J so 1/2 is 8J = 1/2mv2
2 balls are projected from the same launcher as shown.
The work done on the balls is:
Both balls have the same acceleration so the force on the big ball is greater so more work is done on it
2 balls are projected from the same launcher as shown.
Which statement is true about the KE of the balls
same velocity do the big one has more KE
Two balls are accelerated by the same force for 5 seconds
Which statement is true after 5s
The acceleration of the smaller one is greater so it will travel further so more work is done.
How much of Kinetic energy have you understood?
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