posted by Alie on .
There's a bar with length of 6.49m and mass of 5.45kg leaning against a frictionless wall. It makes an angle of 66.08 deg with the ground. A block with mass of 44.98 kg hangs from bar at distance d up from point of contact between bar and floor. The frictional force (us=.371) exerted by the floor keeps the bar from slipping. Find max d that the hanging mass can be attached to bar such that the bar does not slip.
second part: now the hanging mass is detached and removed from the problem. Find minimum angle between bar and ground for which the bar will not slip.
This is my first time on one of these sites and I'm really struggling with physics. will anyone help?
OK. In this, you have to use the conditions for equalibrium.
1) Sum of all vertical forces is zero. Remember at the wall, no vertical force.
2) Sum of all horizontal forces is zero, so you have friction at the bottom, and the wall force at the top.
3) sum of all moments about any point is zero. I would choose the bottom contact point, and sum there. Remember, moment is distance*force*sinTheta where theta is the angle between the distance and force.
These equations will solve for all the unknown forces (friction, wall force, etc).