Question

A 1 200-kg automobile moving at 25 m/s has the brakes applied with a deceleration of 8.0 m/s2. How far does the car travel before it stops?

Answer 1

Answer:

Δx = 39.1 m

Explanation:

• Assuming that deceleration keeps constant during the braking process, we can use one of the kinematics equations, as follows:

        $v_{f} ^{2} - v_{o} ^{2} = 2* a * \Delta x (1)$

        where  vf is the final velocity (0 in our case), v₀ is the initial velocity

        (25 m/s), a is the acceleration (-8.0 m/s²), and Δx is the distance

        traveled since the brakes are applied.

• Solving (1) for Δx, we have:

        $\Delta x = \frac{-v_{o} ^{2} }{2*a} = \frac{-(25m/s)^{2}}{2*(-8.0m/s2} = 39.1 m (2)$