Find the Kinetic Frictional Force on a 9kg Block on an Incline

[wolves5]

A wooden block of mass m = 9 kg starts from rest on an inclined plane sloped at an angle q from the horizontal. The block is originally located 5m from the bottom of the plane. If the block, undergoing constant acceleration down the ramp, slides to the bottom in t = 2 s, and q = 30°, what is the magnitude of the kinetic frictional force on the block?

For this problem, the kinetic frictional force is = to (coefficient frictional force)(normal force). However, there is no coefficient frictional force in this problem. How do I get that? I calculated the normal force to be 88.2. I did F=ma. F=(9 kg) (9.81 m/s2), and got 88.2 N. How do I find the frictional force?

 

[Yuqing]

You have an object under uniform acceleration. Using kinematic equations, you should be able to calculate the magnitude of acceleration from the givens (remember you are given time, distance and initial velocity). After you have the acceleration, you should be able to get a force.