Question

A 1,100 kg car is traveling initially 20 m/s when the brakes are applied. The brakes apply a constant force while bringing the car to rest.
To the nearest kilojoule, how much work is performed by the brakes in bringing the car to rest?

Answer 1

Answer:

Work done = -220,000 Joules.

Explanation:

Given the following data;

Mass = 1100kg

Initial velocity = 20m/s

To find workdone, we would calculate the kinetic energy possessed by the car.

Kinetic energy can be defined as an energy possessed by an object or body due to its motion.

Mathematically, kinetic energy is given by the formula;

$K.E = \frac{1}{2}MV^{2}$

Where,

• K.E represents kinetic energy measured in Joules.

• M represents mass measured in kilograms.

• V represents velocity measured in metres per seconds square.

Substituting into the equation, we have;

$K.E = \frac{1}{2}*1100*20^{2}$

$K.E = 550*400$

K.E = 220,000J

Therefore, the workdone to bring the car to rest would be -220,000 Joules because the braking force is working to oppose the motion of the car.