Instantaneous velocity and friction

[pineapple629]

We need to know the instentaneous velocity formula for a car launched down a hallway. we also need to figure out how to calculate all the friction involved in this. please help.

[Chen]

The car's velocity at a certain moment t is:
\vec V(t) = \vec V_0 + \vec at
The car's acceleration is defined as:
\vec a = \frac{\vec \Sigma F}{m}
In this case the only force on the motion axis (X) is the friction:
\vec a = \frac{\vec f_k}{m} = \frac{-N\mu }{m} = \frac{-mg\mu }{m} = g\mu

Therefore the car's velocity is:
\vec V(t) = \vec V_0 - g\mu t

Does this answer your question?