A car weighing 3 tons moves at a speed of 28.8 km / h. when braking, stops in 6 seconds. Find the braking force.

To solve, you first need to write down the letter formula of Newton’s Second Law, where:

F is the force that acts on the car when braking
a – acceleration (according to the condition of the problem, braking);
m is the mass of the object (in this case, the weight of the car);
V – initial speed of movement of the object
V0 is the final speed of the object;
t is the braking time.
F = m * a.

The amount of deceleration can be expressed in terms of the ratio of speed and time.

Since the final speed is 0, we exclude it.

F = m * (V – V0) / t.

If we substitute the values ​​from the condition into this formula, we get:

F = 3 * 28.8 / 6 = 86? 4/6 = 14.4 kN.

We write down the value of the force in kN, since the weight of the car is indicated in tons.

1 ton = 1000 kilograms.

When converted to Newtons, we get:

F = 14.4 * 100 = 14400 N.


A force equal to 14,400 Newtons acts on the car when braking.

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