







A couch sliding off a truck 
20070430 

From William: A couch with a mass of 1 X 10^2kg 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 .70 meters per second when the ramp angle is 25 degrees, what is the coefficient of kinetic friction between the ramp and couch?
I drew a force diagram and if I did it correctly I identified the forces involved as "mg" (mass x gravity), "Fn" (normal force) and the "Ff" (frictional force). I know that we have the couch sliding down the ramp a .70 m/s but I don't think this a force and I'm not sure how this info fits into the problem. I know that the formula for calculating the coefficient of friction is Ff/Fn. Based upon the force diagram I drew and calculated Fn to be 1082N. I can't seem to get past this point. How do I determine what the frictional force is? Answered by Stephen La Rocque. 





The angle between two forces 
20050119 

From Abraham: One force of 20 pounds and one force of 15 pounds act on a body at the same point so that the resultant force is 19 pounds. Find, to the nearest degree, the angle between the two original forces. Answered by Penny Nom. 





The combined force of two vectors 
20041030 

From Brian: Two teams are playing push ball with a large 8 foot diameter ball. One team exerts a force represented by the vector a = 2i + 5j, and the other team exerts a force represented by the vector b = 8i3j.
1.Determine the direction of movement of the ball if the i axis is due east.
2.Determine the combined force magnitude. Answered by Harley Weston. 





The force of a 5000 tonne lorry 
20041027 

From Aaron: A 50 tonne lorry is parked on a slope with a gradient of 4%.
Due to the self weight of the lorry, what is the force
* acting down the slope
* acting normal (at right angles) to the slope Answered by Penny Nom. 





Levers 
19990113 

From Lane Campbell: 1. Solve for x or y. (a)
<4m><4m><xm >
_____________________________________________________
^ ^ ^ ^
25N 5N ^ 15N
Answered by Jack LeSage. 

