Question

A car and its passengers have a mass of 1200kg it is travelling at 12m/s.

Calculate the increase in kinetic energy when the car increases its speed to 18 m/s.

Show clearly how you work out your answer and give the unit.
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Answer 1

The increase of kinetic energy is 108,000 J

Step-by-step explanation:

Kinetic Energy

Is the energy an object has due to its state of motion. It's proportional to the square of the speed and the mass.

The equation for the kinetic energy is:

`\displaystyle K=(1)/(2)mv^2`

Where:

m = mass of the object

v = speed at which the object moves

The kinetic energy is expressed in Joules (J)

A car has a total mass of m=1,200 kg and travels at v1=12 m/s. Then it increases its speed at v2=18 m/s.

It's required to compute the increase of kinetic energy. We'll calculate both energies K1 and K2 and then subtract them.

`\displaystyle K_1=(1)/(2)1,200*12^2=86,400\ J`

`\displaystyle K_2=(1)/(2)1,200*18^2=194,400\ J`

The increase of kinetic energy is:

`\Delta K=K_2-K_1 =194,400\ J-86,400\ J`

`\Delta K=108,000\ J`

The increase of kinetic energy is 108,000 J