Find TENSION and REACTION FORCE on a Cable Hung Beam | Statics for Engineers

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A beam, supported at one end by an angled cable, and at the other by a pin is loaded with a 50lb block at one end. Calculate the tension force in the supporting cable as well as the force by the pin on the beam.

This statics problem uses the sum of all torques around a point as well as the sum of all forces in both the horizontal and vertical axes to solve for the external forces on the beam.

This problem comes up in physics and engineering courses such as PLTW POE as well as tests such as the AP Physics C Mechanics test and JEE.

[sakthithenna]

shouldnt the T(2)sin 30 for the sum of Y around the pin be negative instead of postive ?

[jeangast]

Very instructive work ! Thanks from France. Please go on !

[gabifallous]

I’m not sure if this is a stupid question but how did you calculate the tension force? 3:12

[PatrickAndersson-pkzd]

What happens if the beam isn't in a horizontal position, but rather pointing 30 degrees upwards with the cable still holding it?

[starvanza]

how does it make sense that at that snapshot in time, when the beam is fully horizontal, there is a vertical normal force component exerted by the wall?

[Rocker_Boy_]

Can you please provide a diagram for the cable's fixing point on the wall? It's really confusing as there is the tension on both sides, the wall reaction etc..

[arcanestudio]

By convention, shouldn't the first equation have (+) signs for counterclockwise torques and (-) signs for clockwise torques.? The equation that follows to solve for tension appears to be correct.

[edilbertyu]

for the Sum of forces at Y is 50n Should be multiplied by the distance of 2m

[xobwlwx]

Why don't we calculate torque exerted by the beam using moment of inertia? I mean the torque of the beam = I*alpha = 1/3mr^2 * F/mr = 1/3*F*r ??