- #1

EchoTheCat

- 21

- 1

## Homework Statement

A block with a mass of 820 g starts from rest at the top of an inclined plane that is 106 cm long and makes an angle of 49.5 degrees with the horizontal. It accelerates uniformly down the ramp and reaches the bottom in 0.89 s. What is the coefficient of kinetic friction on the ramp?

## Homework Equations

x=v

_{o}t +0.5at

^{2}

u

_{k}= F

_{k}/N

## The Attempt at a Solution

In order to calculate coefficient of friction, I need the normal force and F

_{k}.

vo = 0 (starts at rest)

x = 106 cm = 1.06 m

t = 0.89 sec

a = ?

1.06 = 0.5(0.89

^{2})(a)

a = 2.67643 m/s/s

Then, Fk = (2.67643 m/s/s)(0.82 kg) = 2.1947 N

N = (0.82 kg) (9.8 m/s/s) cos 49.5 degrees = 5.219 N

2.1947/5.219 = 0.421