A car weighing 5 tons moves at a speed of 40 km | h, determine the braking force when the speed

| August 15, 2021 | education

A car weighing 5 tons moves at a speed of 40 km | h, determine the braking force when the speed decreases by 20 km | h.

m = 5 t = 5000 kg.

V1 = 40 km / h = 11.2 m / s.

V2 = 20 km / h = 5.5 m / s.

t = 30 s.

Ftr -?

When braking, the car moves only under the influence of the friction force Ftr.

2 Newton’s law will have the form: Ftr = m * a, where m is the mass of the car, a is the acceleration of the car.

Let us write down the formula for acceleration, and for the car: a = (V1 – V2) / t, where V1, V2 are the initial and final speed of movement, t is the time of speed change.

The formula for determining the friction force Ffr will take the form: Ffr = m * (V1 – V2) / t.

Ftr = 5000 kg * (11.2 m / s – 5.5 m / s) / 30 s = 950 N.

Answer: during braking, the friction force is Ftr = 950 N.



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