Question

How much work must be done to stop a 1100-kg car traveling at 112 km/h?(Hint: You will need to convert the speed first.)Answer: ___________ J (round to the nearest whole number)

Answer 1

According to the Work-Energy Theorem, the work done on an object is equal to the change in the kinetic energy of the object:

`W=\Delta K`

Since the car ends with a kinetic energy of 0J (because it stops), then the work needed to stop the car is equal to the initial kinetic energy of the car:

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

Replace m=1100kg and v=112km/h. Write the speed in m/s. Remember that 1m/s = 3.6km/h:

`\begin{gathered} K=(1)/(2)(1100kg)\left(112(km)/(h)*(1(m)/(s))/(3.6(km)/(h))\right)^2=532,345.679...J \\ \\ \therefore K\approx532,346J \end{gathered}`

Therefore, the answer is: 532,346 J.