__FRICTION NOTES__

WHAT IS FRICTION?

What are the types of friction?

What causes it?

Always depends on __________________

Which type of friction is strongest?

How do we measure friction?

What is the coefficicnt of friction?

F_{f}=
m F_{N}

What is the normal force?

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TO ANSWER:

A skier slides down a slope. What force causes him to go down?

What force opposes him?

What changes in environmental conditions might cause a change in the frictional force?

__FRICTION PROBLEMS__

1) D = (__Vi+Vf)__ * T 3)
Vf = Vi + A*T

2

2) Vavg = (__Vi+Vf)__ 4)
D = Vi*T + ½*A*T^{2}

2

5)
Vf^{2 }= Vi^{2} + 2*A*D

Newton’s Laws

Fnet = m * A F1
= F2

Weight = m * g F_{f}= m
F_{N}= m W = m mg ). m= F_{f}/
F_{N}

1) What net
external force is required to give a 25 kg suitcase an acceleration of 2.2 m/s^{2}
to the right? Draw a free body diagram. ** If it is wood on wood (**m = .2

2) What acceleration will you give to a 24.3 kg box if you
push it with a force of 85.5 N? ** If it is aluminum on steel so (**m = .47

3) A 1850 kg car is moving to the right at a constant
velocity of 1.44 m/s. What is the net force on the cart? ** If it is rubber
on concrete so (**m
= .8

4) A man is pushing a 200 Newton box with a force of 50
Newtons along the floor. A dog is pushing against him with a force of 4 N .
What is the acceleration of the box? Draw a free body diagram for the box. ** If
it is glass on glass so (**m = .4

9) A 1200 kg boat moves through the water with two forces
acting on it. One is a 2100 N forward push by the motor, and the other is a
1800 N resistive **friction **force of the
water.

__What is the coefficient of friction?__

** Honors:

13) A block with a mass of 50 kg is sliding down a ramp, **that is wood on wood, ** that is
at an angle of 60 degrees. What is
the component of the force causing it to slide? **What is the force of
of friction?** What is its acceleration?
Draw a picture and force diagram.