# physics

A car that weighs 15,000 N is initially moving at 60 km/hr when the brakes are applied. The car is brought to a stop in 30 m. Assuming the force applied by the brakes is constant, determine the magnitude of the braking force.

1. 👍 0
2. 👎 0
3. 👁 1,477
1. Force x (stopping distance)
= (initial kinetic energy)
= (1/2) M V^2

For the kinetic energy, you will have to convert the weight (N) to mass (kg) and the 60 km/hr initial velocity to m/s. I assume you know how to do this.

1. 👍 0
2. 👎 0
2. Thanks you for your quick reply. I really appreciated it, although I still cannot find the way to get the answer which is 7,086.7 N.

1. 👍 0
2. 👎 0
3. m = 15,000/9.8 = 1530 kg
v = 60,000 m/3600 s = 16.7 m/s

(1/2) m v^2 = 212,500 Joules

F (30) = 212,500
F = 7083 N

1. 👍 0
2. 👎 0
4. Make certain you convert the weight 15000N to mass.

Force= .5 M V^2/distance=
= .5 (Weight/g)V^2 /distance3=
= .5(15,000/9.8)*16.66^2 /30
and that gives the right answer.

1. 👍 0
2. 👎 0
👨‍🏫
bobpursley

## Similar Questions

1. ### physics

A car moving at 50 km/h skids 15 m with locked brakes. Show that a car moving at 150 km/h will skid 135 m with locked brakes. (Hint: The force doing work during the skidding is the same for both speeds. Use the work–energy

2. ### Physict

This question is similar to some on driver's-license exams: A car moving at 50 km/h skids 15 m with locked brakes. Show that with locked brakes at 150 km/h the car will skid 135 m.

3. ### Physics

A car is traveling at 7.0 m/s when the driver applies the brakes. The car moves 1.5 m before it comes to a complete stop. If the car had been moving at 14 m/s, how far would it have continued to move after the brakes were applied?

4. ### physics

A car weighing 1.0 x 10^4N is parked on a 34 degree slope. The brakes fail and the car starts to slide down the hill. Assume no friction. Show your work, and determine a) the acceleration of the car, and b) after it has moved 28.0

1. ### Physics

This question is typical on some driver’s license exams: A car moving at 40 km/h skids 14 m with locked brakes. How far will the car skid with locked brakes at 100 km/h? Assume that energy loss is due only to sliding friction.

2. ### Physics

Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 3.6 m/s2 for 4.5 seconds. It then continues at a constant speed for 7.3

3. ### physics

This question is typical on some driver's license exams: A car moving at 50km/hr skids 15m with locked brakes.How far will the car skid with locked brakes at 120 km/h?

4. ### Physics

A 10,000 kg railroad car traveling north at 10 m/s collides with a 5,000 kg rail car also moving north but at an unknown speed. After the collision, the two cars lock together and move north at 8 m/s. How fast was the second car

1. ### physics

A 1000 kg car traveling is at 40.0 m/ s. To avoid hitting a second car the driver slams on his brakes. The brakes provide a constant friction force of 8000 N. ( a) Find the minimum distance that the brakes should be applied in

2. ### science

The driver of a 1.00X103 kg car traveling on the interstate at 35.0 m/s slams on his brakes to avoid hitting a second vehicle in front of him, which had come to rest because of congestion ahead. After the brakes are applied, a

3. ### Physics

A 1,100 kg car is traveling at 15 m/s when the brakes are suddenly applied. How far a distance will it travel if the brakes can exert a force of 6,000 N?

4. ### Physics

During a road test,a driver brakes a 1420kg car moving at 64.8km/h [W]. The car slows down and comes to a stop after moving 729m [W]. What is the net force acting on the car?