A 2000-kg car experiences a braking force of 10,000 N and skids to a stop in 6 seconds.The speed of the car just before the brakes were applied was
A)1)2 m/s.
B)15 m/s.
C)30 m/s.
D)45 m/s.
E)none of these

Question

Quizplus · Accepted Answer

We can use the equation:

F = ma

where F is the braking force, m is the mass of the car, and a is the deceleration.

We can rearrange the equation to solve for a:

a = F/m

a = 10000 N / 2000 kg

a = 5 m/s^2

We can then use the kinematic equation:

v_f = v_i + at

where v_f is the final velocity (0 m/s), v_i is the initial velocity (what we're trying to solve for), a is the deceleration (-5 m/s^2), and t is the time (6 s).

Rearranging the equation to solve for v_i:

v_i = v_f - at

v_i = 0 m/s - (-5 m/s^2)(6 s)

v_i = 30 m/s

Therefore, the speed of the car just before the brakes were applied was 30 m/s.

A 2000-Kg Car Experiences a Braking Force of 10,000 N