Need help, I've been stuck on this for awhile

Difference between series and parallel circuits

Aparticle moves in a circle 1.50 m in radius . through what angle in radians does it rotate if it moves through an arc length of 2.50m? what is the angle in degrees?

The drag force, fd, imposed by the surrounding air on a vehicle moving with velocity v is given by fd = cdaρv 2/2 where cd is a constant called the drag coefficient, a is the projected frontal area of the vehicle, and ρ is the air density. an automobile is moving at v = 80 kilometers per hour with cd = 0.28, a = 2.3 m2, and ρ = 1.2 kg/m3.