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## Homework Statement

A 4.5 kg block is on an incline with a coefficient of static friction of 0.50. The angle that the ramp makes with the horizontal is increased gradually, until the block begins to slide down the ramp. If you know that the coefficient of kinetic friction between the block and the plane is 0.10, find the time it will take the block to slide down the ramp a distance of 0.65 m starting from rest.

## Homework Equations

Kf = (coef of frict)*m*g*cos(theta)

## The Attempt at a Solution

tan^-1 (.5) = 26.6

theta = 26.6 degrees

F_g = mg

F_g = (4.5)*(9.81) = 44.1 N

F_gx = 44.1*sin(26.6) = 19.7

a_x = 19.7 N / 4.5 kg = 4.39 m/s^2

4.39 - (coef of frict)*m*g*cos(theta)

4.39 - (.1)(4.5)cos(26.6)

4.39 - .402 = 3.99 m/s^2

d = .65

d = 1/2at^s

.65 = 1/2 (3.99) t^2

.65 = 1.995t^2

t^2 = .326

t = .571 seconds.

I'm really confused, as we haven't covered this stuff in lecture, yet we have labs that deal with it. I'm sorry if I completely fudged up something because I don't know what I'm doing...