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.