How would I find static friction given the following information: V= 45km/hr Time to decelerate completely from 45km/hr: 3.5s The motion of the object given is of a moving vehicle. There is a cup on the dashboard inside the vehicle that moves only when deceleration time is less than or equal to 3.5s. From this information how could I solve for static friction between the cup and the dashboard? I started by converting the velocity to m/s and found the acceleration to be be 3.57m/s^2 in the negative x direction. I do not know how to go from here...please help.