A 1000 kg car is travelling at 72 km/h when the brakes are applied. It comes to a stop in a distance of 40m. What is the average braking force of the car?
I seriously have no idea how to do this. Anyone that could help me solve this STEP-BY-STEP and please don't be too fast, i admit im an epic noob in physics :/
I seriously have no idea how to do this. Anyone that could help me solve this STEP-BY-STEP and please don't be too fast, i admit im an epic noob in physics :/
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First, convert 72km/h to m/s
72 km/h * 1000m/1km * 1h/3600s = 20 m/s
By Newton's second law, F = ma. You have the mass of the car, but not the acceleration. So first, we find the acceleration.
Using an equation of kinematics, we have:
(final velocity)^2 = (initial velocity)^2 + 2*acceleration*(distance travelled)
Since the car came to a halt, the final velocity is 0.
0 = (20m/s)^2 + 2*acceleration*40m
-400 = 80a
a = -5 m/s^2
The acceleration is negative! Don't worry, this only means that the car is slowing down, which is quite logical since you are stepping on the brakes.
Back to Newton's second law, we have
F = ma
F = 1000kg * 5 m/s^2 = 5000N
Thus, the average braking force of the car is 5000N.
72 km/h * 1000m/1km * 1h/3600s = 20 m/s
By Newton's second law, F = ma. You have the mass of the car, but not the acceleration. So first, we find the acceleration.
Using an equation of kinematics, we have:
(final velocity)^2 = (initial velocity)^2 + 2*acceleration*(distance travelled)
Since the car came to a halt, the final velocity is 0.
0 = (20m/s)^2 + 2*acceleration*40m
-400 = 80a
a = -5 m/s^2
The acceleration is negative! Don't worry, this only means that the car is slowing down, which is quite logical since you are stepping on the brakes.
Back to Newton's second law, we have
F = ma
F = 1000kg * 5 m/s^2 = 5000N
Thus, the average braking force of the car is 5000N.