A car at 60 km/h does not carry twice the energy of one at 30 km/h, it carries four times as much. That is why stopping distances grow so sharply with speed. Kinetic energy depends on the square of the speed, so small increases in speed mean large jumps in energy.
Kinetic energy is the energy of a moving object: KE = ½mv², measured in joules. The velocity is squared, so doubling the speed multiplies the kinetic energy by four, not two.
Kinetic energy is the energy a body has because of its motion: half the mass multiplied by the speed squared.
The speed is squared, so doubling the speed multiplies the kinetic energy by four.
Change the mass and the speed and read the kinetic energy. Notice how a small rise in speed sends the energy up far more steeply than the same rise in mass.
Four quick checks on the equation and the square-of-speed effect. Each correct answer earns XP and lights this skill on your star map.
Kinetic energy is calculated using the equation...
In KE = ½ m v², doubling the speed multiplies the kinetic energy by...
Kinetic energy is measured in...
The kinetic energy of a moving object depends on...
The defining equation, and the form rearranged for speed:
A 1500 kg car travels at 8.0 m/s. Find its kinetic energy.
Square the speed before multiplying, and do it first. A common slip is to work out ½mv and forget the square, or to square the whole expression. Only the speed is squared. Because of that square, doubling the speed multiplies the kinetic energy by four, and tripling it multiplies the energy by nine.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
A 2.0 kg ball moves at 3.0 m/s. Its kinetic energy is...
A car has 20 kJ of kinetic energy at 10 m/s. At 20 m/s, with the same mass, its kinetic energy is...
A 0.50 kg ball has 25 J of kinetic energy. Its speed is...
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