Question

A 2.00 m long uniform steel bar rests on the ground and against the wall. Both the wall and the ground are frictionless. THe steel bar makes an angle of 50 degrees with the ground. To keep the steel bar in static equilibrium, a horizontal wite attaches the steel bar at 0.500m from the bottom to the wall. The mass of the steel bar is 60kg.

a) Draw a free body diagram showing all the forces on the steel bar b) Using total force =0 write down the equations for both x and y directions. Then solve or simplify the equations as much as you can. c) Choose a point at the axis of rotation and write down all the torques (with sign) based on your choice of rotational axis. Then using total toorque=0, solve all the unknown forces on the steel bar

Answer 1

PART A

PART B

Refer the figure above, we know for equilibrium condition the sum of vertical and horizontal forces should be zero.

Also, we are given:

mass of bar

length of bar

angle with the ground,

Height of wire from ground:

We get for horizontal forces:

..............EQ1

For vertical forces:

...........EQ2

PART C

Refer the figure again, we know for equilibrium condition the sum of moments about a point should be zero. We select point 'B'.We need the perpendicular distance from the chosen point to the forces. So we need to find

We get for moments about the point A (clockwise negative and counter-clockwise positive):

using EQ1 ,