Police investigators, examining the scene of an accident involving two cars, measure 72-mlong skid marks of one of the cars, which nearly came to a stop before colliding. The coefficient of kinetic friction between rubber and the pavement is about 0.80. Estimate the initial speed of that car assuming a level road.

The initial speed of car is 33.6

Explanation:

Given :

Distance travel by cars m

Coefficient of kinetic friction

From the equation of kinematics,

Where final speed here it is zero ( ), acceleration of car

From FBD diagram we can write,

Here minus sign represent friction oppose the motion,

                  ( ∵ )

Put the value of acceleration in above equation and find initial velocity,

Therefore, the initial speed of car is 33.6

0.93xc=0.93x3x10^8m/s

2.54cm is 1 inch

360seconds i 1 hr