Question

What is the kinetic energy of a car with a mass of 6 tons, moving at a speed of 72 km/h?

Answer 1

We are asked to determine the kinetic energy of a car given its mas and its velocity. To do that we will use the following formula:

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

Where:

`\begin{gathered} m=\text{ mass} \\ v=\text{ velocity} \\ K=\text{ kinetic energy} \end{gathered}`

We will convert the mass from tons to kilograms using the following conversion factor:

`1ton=1000kg`

Multiplying by the conversion factor we get:

`6ton*(1000kg)/(1ton)=6000kg`

Now, we convert km into meters and hours into seconds using the following conversion factor:

`\begin{gathered} 1km=1000m \\ 1h=3600s \end{gathered}`

Multiplying by the conversion factors we get:

`72(km)/(h)*(1000m)/(1km)*(1h)/(3600s)=20(m)/(s)`

Now, we substitute in the formula for kinetic energy:

`K=(1)/(2)(6000kg)(20(m)/(s))^2`

Solving the operation :

`K=1200000J`

Therefore, the kinetic energy is 1200000 Joules.