At an accident scene on a level road, investigators measure a car's skid mark to be 84 m long. It was a rainy day and the coefficient of friction was estimated to be 0.36.

Step-by-step explanation:

We know:

KE=12mv2=Fd

KE=  

2

1

mv  

2

=Fd

Where Fd=umgdFd=umgd Thus,

12mv2=umgd

2

1

mv  

2

=umgd

12v2=ugd

2

1

v  

2

=ugd

v2=2ugd

v  

2

=2ugd

v=2ugd−−−−√

v=  

2ugd

v=2(0.3)(9.81)(78)−−−−−−−−−−−−−√

v=  

2(0.3)(9.81)(78)

v=21.4m/s

v=  

21.4m/s

Part B

The cars mass does not matter because we can see that the mass cancels out from both sides of the equation.

answer: procent 54 wynosi 33,33%

2nd one in the first row is correct