# Physics

posted by .

A 1000kg car is traveling along a level road at 20.00ms, when the brakes are applied long enough to do 50000 J of work.

1) what is the initial kinetic energy of the car?

2) if the car moved 100m while the brakes where applied, what was the average force exerted on the brakes.

• Physics -

In itial KE = (1/2)M V^2

Your 20.00 ms must be 20.00 m/s.

The brakes do not DO work; they absorb heat equal to the work done by the car (on the brakes) while slowing down.

Force x distance = Kinetic energy loss

Solve for the force.

• Physics -

Thank you.

## Similar Questions

1. ### motion problem (please check)

A 8000N car is traveling 12 m/s along a horizntal road when the brakes are applied. The car skids to a stop in 4.0s. How much kinetic energy does the car have. my work: W= 8000N/9.18m/s mass= 815.49 kg Kinetic energy= (1/2mv^2-1/2mv^2) …
2. ### Physics

The brakes are applied to a car traveling on a dry, level highway. A typical value for the magnitude of the car's acceleration is 5.35 m/s2. If the car's initial speed is 29.1 m/s, how long does it take to stop and how far does it …
3. ### physics

A car travels along a roadwith a speed of v=25 m/s (about 50 mi/h). The coefficient of kinetic frictionbetween the tires and the pavement is mu k=.55. a). If the driver applies the brakes and the tires "lock up" so that they skid along …
4. ### physics

A car has an initial speed of 23.0 ms-1. In addition, there is also wind blowing in direction similar to the car with a force of 30 N. If the brakes are applied and the car skidded for 10 meters before coming to a halt, determine the …
5. ### physics

The brakes are applied to a car traveling on a dry, level highway. A typical value for the magnitude of the car's acceleration is 4.75 m/s2. If the car's initial speed is 32.1 m/s, how long does it take to stop and how far does it …
6. ### Physics

a driver sees a horse on the road and applies the brakes so hard that they lock and the car skids to a stop in 24 m. the road is level and the coefficient of kinetic friction between the tires and the road is 0.7. How fast was the …