A car of mass 900 Kg is moving with a velocity of 10 m/s. It is brought to rest at 25 m distance by applying the brakes. Calculate the acceleration. Why is it negative? How much force is required to stop the car?​

Assumption: the acceleration of this vehicle is constant until it comes to a stop.

Acceleration: .

The acceleration of this vehicle is negative because the velocity of this vehicle is decreasing over time.

Explanation:

Assume that the acceleration of this vehicle, , is constant. The SUVAT equations would apply.

The time required for braking is neither given nor required. Hence, make use of the SUVAT equation to relate , , , and .

Rearrange this equation to find an expression for , the acceleration of this vehicle:

.

Acceleration is the rate at which velocity changes over time.

The velocity of the vehicle in this question is getting smaller over time. Hence, the rate of change of the velocity of this vehicle (that is, the acceleration of this vehicle) would be a negative number.

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