a car leaves skid marks 84 m long on the highway. Assuming a deceleration of 7.50 m/s2, estimate the speed of the car just before braking.

Vo = sqrt(2 a X) = 35.5 m/s

To estimate the speed of the car just before braking, we can use the basic kinematic equation that relates distance, acceleration, and initial velocity.

The equation we will use is:

v^2 = u^2 + 2as

Where:
v - final velocity (which is 0 m/s because the car comes to a stop)
u - initial velocity (which is what we need to find)
a - acceleration (given as -7.50 m/s^2 because the car decelerates)
s - distance (given as 84 m)

Rearranging the equation, we have:

u^2 = v^2 - 2as

Substituting the known values:

u^2 = 0 - 2(-7.50)(84)

Simplifying:

u^2 = 0 + 1260

u^2 = 1260

Taking the square root of both sides:

u = √1260

u ≈ 35.5 m/s

Therefore, the estimated speed of the car just before braking is approximately 35.5 m/s.