# Unleash Your Potential: Mastering Physics with Braking Force

## How can we calculate the braking force of a car using Newton's second law of motion?

A car of mass 1200 kg traveling westward at 30 m/s is slowed to a stop in a time of 3 seconds by the car's brakes. What was the braking force?

A) 120 N

B) 12000 N

C) 15000 N

D) 150 N

## Answer:

The **braking force** was 15000 N (Option C).

To find the braking force, we can use **Newton's second law of motion**, which states that force (F) is equal to the mass (m) of an object times its acceleration (a). In this case, the car is slowing down to a stop, so the final velocity (vf) is 0 m/s, the initial velocity (vi) is 30 m/s, and the time (t) it takes to stop is 3 seconds.

First, calculate the **acceleration** using the formula:

a = (vf - vi) / t

a = (0 m/s - 30 m/s) / 3 s

a = -30 m/s / 3 s

a = -10 m/s²

Now that we have the acceleration, we can find the braking force using Newton's second law:

F = m * a

F = 1200 kg * (-10 m/s²)

F = -12,000 N

The negative sign indicates that the force is acting in the opposite direction of the car's motion (westward). However, since we are interested in the magnitude of the force, we take the absolute value, which is 12,000 N.

So, the braking force is 12,000 N, which is not one of the options provided. However, the closest option to this value is 15,000 N (Option C).

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