1. A couch with a mass of 1x10^2 kg is placed on an adjustable ramp connected to a truck. As one end of the ramp is raised, the couch begins to move downward. If the couch slides down the ramp with an acceleration of 0.70 m/s^2 when the ramp angle is 25 degrees, what is the coefficient of kinetic friction between the ramp and couch? (g = 9.81 m/s^2)
2. A crate is carried in a pickup truck traveling horizontally at 15.0 m/s. The truck applies the brakes for distance at 28.7 m while stopping with uniform acceleration. What is the coefficient of static friction between the crate and the truck bed, if the crate does not slide?
1. F = ma
u(kinetic) = Force(kinetic)/Force(normal) = Force(kinetic)/(mg)
2. Either v(final) = v(initial) + a(t)
distance = 0.5(initial velocity + final velocity)(t)
distance = v(inital)(t) + 0.5a(t)^2
-I think those are the three formulas I have for constant uniform acceleration. How do I choose which one to use? And what to do after finding the acceleration?
The Attempt at a Solution
F = (1 x 10^2 kg)(0.70 m/s^2)
F = 70 N
Is this right? How I involve the angle?
2. vf = vi + at
-15 = 430.5a
a = -0.0348
How can you find normal force? I know it's (mg), but is there another way? I bad at drawing diagrams, and working it out.