As a section of an workout program to toughen their pectoral muscles a person stretches a spring which has a spring constant k = 520 n/m. write an equation for the work necessary to stretch the spring from the relaxed state to a distance x1.

You are driving to the grocery store at 20 m/s. you are 110m from an intersection when the traffic light turns red. assume that your reaction time is 0.50s and that your car brakes with constant acceleration. how far are you from the intersection when you begin to apply the brakes? what acceleration will bring you to rest right at the intersection? how long does it take you to stop after the light changes? the known values: vi=20m/s xi=110m t=.50s vf=0m/s xf=0m a=?