Answer:
Explanation:
a is the acceleration
μ is the coefficient of friction
Acceleration of the object is given by

Velocity at the bottom

after travelling 4m , its velocity becomes 0



Coefficient of kinetic friction
μ = F/N

Therefore, the Coefficient of kinetic friction is 0.31
Force can alter its direction,slow or stop it you could say it can change its velocity
I think it is A. but then you can also produce your own energy
Your answer is.......a car moved 60 km East and 90 km in west.