If you are driving at 20 m/s and slam on your brakes and skid at 0.5g to a full stop, the skidding time is about
A) 3 s.
B) 4 s.
C) 5 s.
D) 6 s.
E)greater than 6 s.

Question

Quizplus · Accepted Answer

We can use the kinematic equation:

v_f^2 - v_i^2 = 2aΔx

where v_i is the initial velocity, v_f is the final velocity (0 in this case), a is the acceleration due to braking (0.5g or 4.9 m/s^2), and Δx is the stopping distance. We can solve for Δx:

Δx = v_i^2 / 2a

Plugging in v_i = 20 m/s and a = 0.5g = 4.9 m/s^2, we get:

Δx = (20 m/s)^2 / (2 x 4.9 m/s^2) ≈ 41 m

The skidding time can be found from the equation:

Δx = (1/2)at^2

where t is the skidding time. Solving for t:

t = sqrt(2Δx/a)

Plugging in Δx = 41 m and a = 0.5g = 4.9 m/s^2, we get:

t = sqrt(2 x 41 m / 4.9 m/s^2) ≈ 4 s

Therefore, the skidding time is about 4 s.

If You Are Driving at 20 M/s and Slam on Your