A2000 kg car experiences a constant braking force of 10,000 n, and comes to a stop in 6 sec. what would have been the speed of the car just before the brakes were applied?

The solution for this problem is:
We will be using the formula for force which is F = ma 

=>10,000 = 2000 * a 

but we need to solve for acceleration so divide both sides by 2000, we will get:

=>a = 5 m/s^2 
Let the initial velocity was u m/s 

=>By v = u - at 

=>0 = u - 5 x 6 

Since acceleration is constant the velocity can be computed by multiplying the acceleration by 6 seconds. 
=>u = 30 m/s

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