When solving kinetic energy problems, you may be asked to find 3
variables. These variables are the kinetic energy, the mass, or the
Problem # 1:
Suppose a car has 3000 Joules of kinetic energy. What will be its kinetic energy if the speed is doubled? What if the speed is tripled?
We already proved in kinetic energy lesson that whenever the speed is doubled, the kinetic energy is quadrupled or four times as big.
4 × 3000 = 12000
Therefore, the kinetic energy is going to be 12000 joules.
Let v be the speed of a moving object. Let speed = 3v after the speed is tripled.
9 × 3000 = 27000
Therefore, the kinetic energy is going to be 27000 joules.
Problem # 2:
Calculate the kinetic energy of a 10 kg object moving with a speed of 5 m/s. Calculate the kinetic energy again when the speed is doubled.
Problem # 3:
Suppose a rat and a rhino are running with the same kinetic energy. Which one do you think is going faster?
The only tricky and hard part is to use the kinetic energy formula to solve for v.
Multiply both sides by 2
Problem # 4:
The kinetic energy of an object is 8 times bigger than the mass. Is it possible to get speed of the object?
Think carefully and try to solve this problem yourself.If you still cannot do it, click here to see the solution.