What is the acceleration of your car rolling downhill on an 8.00% slope (so that

Question

What is the acceleration of your car rolling downhill on an 8.00% slope (so that tan theta = 0.08?

If the car rolls over 5.00 mile length distance along this sope, what speed does it gain starting from rest? (Neglect rolling and drag here.)

I'm confused on the above because I don't know the mass of the car.

Then they ask:  How much is the air drag on a m=1500 kg car when it coasts downhill 5.00 degress AT A CONSTANT SPEED of 60 mph.  Neglect friction here.

Please give the answer and HOW TO DO THE PROBLEM.  

Explanation / Answer

tanA =0.08

A =4.57 degrees

a = gsinA = 9. 8x sin4.57 = 0.782 m/s2

v^2 - 0 =2 x 0.782 x 5 x 1609   ( 1 mile = 1609 m )

v = 112.14 m/s

constant speed so acc. a= 0

mgsinA - drag force = 0

drag force = 1500 x 9.8 x sin5 = 1281.20 N

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