Equilibrium. How to solve for four variables?

AI Thread Summary
To solve for the tension in the wire supporting a uniform beam, apply the conditions for equilibrium, specifically ΣF=0 and ΣTorque=0. The free body diagram reveals four equations, allowing for the calculation of the tension and the hinge's force components. The vertical and horizontal components of the tension must balance the weight of the beam and the hinge forces. By breaking down the forces into components and calculating torques, two equations with two unknowns can be established. Converting units from feet to meters may be necessary for accurate calculations.
moose726
Messages
3
Reaction score
0

Homework Statement


One end of a uniform beam weighing 288 N and 3.12 feet long is attached to a wall with a hinge. The other end is supported by a wire making equal angles of 30° with the beam and wall.

(a) Find the tension in the wire.

(b) What is the horizontal component of the force of the hinge on the beam?

(c)What is the vertical component of the force of the hinge on the beam?

Homework Equations


\SigmaF=0
\SigmaTorque=0

The Attempt at a Solution


I drew a free body diagram of the beam and the components of the forces from tension and the hinge. From this I got four equations:
\SigmaFx = Fx-Tx = 0
\SigmaFy = Fy+Ty-mg = 0
\Sigma Torque = 118.5+.4754Tx-.823Ty=0 (T is tension, this torque is with the hinge as the origin.)
Fy=Fxtan(30)
I'm not sure how to solve for each variable with these equations.
 
Physics news on Phys.org
The easiest way to think about this is to break it into parts. Instead of solving for multiple unknowns just solve for part a.

The vertical component of tension must be perfectly balanced by the vertical component of the torque of the beam. Same goes for the horizontal tension.

You can calculate the torque in the x and y directions and then you have two equations with two unknowns.
 
Take the components of tension T along and perpendicular to the beam. Similarly take the components of the weight of the beam, which acts at the center of the beam.
The perpendicular components contribute to the torque, while components along the beam does not contribute to the torque.
Apply the condition for equilibrium and solve for T.
Convert the unit of length from ft to m.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top