Name: ______________________

Quiz 4

02/22/2005

Ch. 4-5

1)      A man pulls a box with a massless rope at an angle of 30 degrees to the ground.   The box has a mass of 100kg and the static coefficient of friction μs=0.6 and a kinetic coefficient of friction μk=0.3. (note: Weight and tension are forces and forces are vectors.)

a)      Draw two free body diagrams one for the box and one for the rope.

b)      What is the weight of the box?

c)      What is the normal force on the box?

d)      What is the maximum friction force on the stationary box?

e)      What is the minimum pulling force needed to move the box?

f)        What is the pulling force required to keep the box moving at constant speed?

g)      What is the tension on the rope when the box is moving at a constant speed?

2)      A 300kg sled is on a 30-degree hill.  The kinetic coefficient of friction μk between the sled and snow is 0.1.

a)      What is the net force on the sled?

b)      If the sled is started moving with a velocity of 1m/s, will it continue to move?

c)      What is its speed after 10s?