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Forces: Standing on a beam

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Wize University Physics Textbook (Master) > Angular / Rotational Motion

Torque

3 Activities

A horizontal beam with a length of 8.0 meters and weight of 200 N is attached to a wall by a pin connection. Its far end is attached to the cable that makes angle of 53 degrees with the beam. A person of weight 600 N stands 2.0 meters away from the wall. What is the tension of the cable (T) and the magnitude of the force that wall applies on the beam (R), respectively?

Hint: The total reaction force is the sum of a normal force (perpendicular to the wall) and a friction force (parallel to the wall). So the net reaction force will be at an angle. (In this problem we are not ignoring friction at the wall). In this problem, there are a few ways to solve it; but you can just treat the reaction force as a single force that provides a single torque at an angle to find the answer.


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More Torque Questions:
Torque on a Circular Current Loop
Practice: Torque on a Circular Current Loop
A circular loop of radius 10.5 cm and 40 turns has a current of 2.50 A flowing through the coil. A magnetic field of strength 3.4 T acts at an angle of 35º to the normal of the plane of the loop. What is the magnitude of the net torque acting on the loop?
Practice: Torque on a Circular Current Loop
A circular loop of radius 10.5 cm and 40 turns has a current of 2.50 A flowing through the coil. A magnetic field of strength 3.4 T acts at an angle of 35º to the normal of the plane of the loop. What is the magnitude of the net torque acting on the loop?
One end of a uniform 4.0 m-long rod of weight w{\small w} is supported by a cable at an triangle of θ = 37°{\small \theta\ =\ 37\degree}with the rod. The other end rests against a wall, where it is held by friction, as shown. The coefficient of static friction between the wall end the rod is μs = 0.50.{\small \mu_s\ =\ 0.50.} Determine the minimum distance x{\small x} from point A at which an additional weight w{\small w} (the same as the weight of the rod) can be hung without causing the rod to slip at point A. Enter your answer in meters to the appropriate number of sig figs.
Practice: Balanced beam
A uniform 90 kg beam is resting on two supports as shown below. The supports are 20 cm and 80 cm away from the two ends of beam. If the beam is 180 cm, what are the forces acting on the beam from supports A and B?
A 3.0 m ladder of mass 12 kg rests against a frictionless wall. The coefficient of friction between the ladder and the floor is 0.60. Assume there is no friction between the wall and the ladder. What is the smallest angle that the ladder can make with the ground if the ladder is to remain at rest? (Enter your answer in degrees)
Forces: Torque
A seesaw of length 5m is supported at the center. A child of mass 35kg is sitting on one end. A second child of mass 45kg comes to play. Where should the second child sit in order to balance the seesaw? Enter your answer in meters, measured from the pivot axis of the seesaw.
Find the net torque on the wheel below about the axle through Operpendicular to the page, taking a = 10.0 cm and b = 25.0 cm. (Note for clarification: the 12.0 N force is acting directly above the axis O, at an angle from that point.) Give your answer in units of Nm to the appropriate number of significant figures.
Calculate the net torque (magnitude and direction) on the beam through the point labelled O (i.e. an axis perpendicular to the page at point O) and (b) through an axis through C perpendicular to the page. Give your answers in Nm.
A mass-less string is wrapped several times around a Cylinder . If the free end of the string is held in place and the Cylinder is released form rest, the string unwinds and the Cylinder descends. What is the acceleration of the Cylinder ?
A thin uniform rod (length=1m, mass = 5kg) is pivoted about a horizontal, frictionless pin through one end of the rod. The rod is released when it makes an angle of 60°60\degree above the horizontal. What is the angular acceleration of the rod at the instant it is released? (pick the closest answer)
A 10 kg mass is hanging from a rope wrapped around a pulley. The falling mass causes the pulley to rotate. The mass of the pulley is 2 kg. What is the acceleration of the falling mass, and what is the tension of the rope?
Practice: Condition of Static Equilibrium
A 3.0 m ladder of mass 12 kg rests against a frictionless wall. The coefficient of friction between the ladder and the floor is 0.60. What is the smallest angle that the ladder can make with the ground if the ladder is to remain at rest? (in degrees) Neglect the friction between the ladder and the wall.
Is the force exerted by the tendon attached to the forearm to hold the forearm horizontal greater than, equal to, or less than the weight of the forearm?
If a man can push with a maximum force of 90 N, how far from the door's rotation axis must he apply this force if 110-Nm torque is needed to start rotating a revolving door?
A wooden beam of mass 150 kg and length 10m is suspended from a horizontal wall support at the left end and connected by a cable to the same wall at the right end. The cable makes an angle of 45º with the horizontal. A person of mass 42 kg stands on the beam 2.5 m from the left wall. A 25 kg child also rests on the beam, at 7m from the left wall. Calculate the tension in the rope and the force exerted by the wall on the beam.
Newton’s First Law does not apply to rotating objects
torque
Calculate the net torque (magnitude and direction) on the beam through the point labelled O (i.e. an axis perpendicular to the page at point O) and (b) through an axis through C perpendicular to the page. Give your answers in Nm.
Torque due to a Magnetic Field
A circular loop of radius 10.5 cm and 40 turns has a current of 2.50 A flowing through the coil. A magnetic field of strength 3.4 T acts at an angle of 35º to the normal of the plane of the loop. What is the magnitude of the net torque acting on the loop?