Question

6. A car begins traveling at 15 m/s before it has engine trouble and has to stop.the force it takes the car to stop is 15,000 N what is the mass of the car?

Answer 1

As told in the answer above

Answer 2

We are given that a car is moving at a speed of 15 m/s and it brakes completely. We are asked to determine the mass of the car. To do that we need first to determine the acceleration of the car. To do that we will use the following equation of motion:

`v_f=v_0+at`

Where:

`\begin{gathered} v_f=\text{ final velocity} \\ v_0=\text{ initial velocity} \\ a=\text{ acceleration} \\ t=\text{ time} \end{gathered}`

Now we solve for the acceleration first by subtracting the initial velocity from both sides:

`v_f-v_0=at`

Now we divide both sides by the time:

`(v_f-v_0)/(t)=a`

Since the car stops this means that the final velocity is zero, therefore:

`-(v_0)/(t)=a`

replacing the value of the initial velocity we get:

`(-15(m)/(s))/(t)=a`

Now we use Newton's second law to determine the mass:

`F=ma`

Now we divide both sides by the acceleration:

`(F)/(a)=m`

Now we replace the known values:

`(-15000N)/(-(15(m)/(s))/(t))=m`

Solving the operations we get:

`(1000)/(t)kg=m`

Where "t" is the time it takes the car to stop completely.