Direction of Reaction Force on Beam in Torque Problem

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In summary, the conversation discusses a problem involving a beam and a wall. The beam is not in equilibrium and the direction of the force exerted by the wall on the beam is being questioned. It is determined that there is a force and torque exerted by the wall on the beam, and the direction of the force is determined by the net force acting on the beam according to Newton's first law. The conversation also touches on the concept of torque and equilibrium.
  • #1
DANIELLYMA
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Here's an image of the problem I trying to do.

http://img339.imageshack.us/img339/1765/torquequestionqv0.th.gif [Broken]

I'm wondering if there is a force exerted by the wall on the beam, and if so in which direction? I think it's pointed upward to the right, but I'm not too sure.

Any help would be appreciated.
 
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  • #2
DANIELLYMA said:
Here's an image of the problem I trying to do.

http://img339.imageshack.us/img339/1765/torquequestionqv0.th.gif [Broken]

I'm wondering if there is a force exerted by the wall on the beam, and if so in which direction? I think it's pointed upward to the right, but I'm not too sure.

Any help would be appreciated.
There is a force and a torque exerted by the wall on the beam. The magnitude and direction of each is determined from equilibrium considerations...sum of forces = 0 and sum of torques =0. Don't confuse torques wuth forces. The force of the wall on the beam does not have a rightward component.
 
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  • #3
I don't undestand what you mean. The beam is not in equilibrium, and I know torque caused by the wall is zero, but I was wondering what's the direction of the force exerted by the wall.
 
  • #4
DANIELLYMA said:
I don't undestand what you mean. The beam is not in equilibrium, and I know torque caused by the wall is zero, but I was wondering what's the direction of the force exerted by the wall.
What makes you say the beam is not in equilibrium? The beam is supported into the wall which exerts a torque about point P, which is equal and opposite to the torque caused by the beam's weight about point B. Now you wish to go one step further and determine the direction of the force on the wall on the beam. What does Newton's first law tell you about in which direction the net force of the wall on the beam must be??
 
  • #5
My teacher told me it wasn't in equilibrium since there is a torque.
 
  • #6
DANIELLYMA said:
My teacher told me it wasn't in equilibrium since there is a torque.
There are two torques...one caused by the weight (10(9.8)(2) = 196n.m), and one caused by the wall (-196n.m). Bt this is really an engineering statics question, and i suppose your teacher might argue that the beam is rotating about a pin at joint P , in which case, no torque would be supplied by the wall. But nevertheless, there still exists a force at the wall acting on the beam, and since the beams weight always acts vertically down, then the reaction force of the wall on the beam must act --------(fill in the blank).
 

1. What is torque?

Torque is a measure of the rotational force applied to an object. It is a vector quantity, meaning it has both magnitude and direction. In simple terms, torque is the force that causes an object to rotate around an axis.

2. What is a free body diagram (FBD)?

A free body diagram is a visual representation of the forces acting on an object. It is used to analyze the forces and motion of an object by showing all external forces acting on the object and their direction. FBDs are commonly used in physics and engineering to solve problems involving forces and motion.

3. How do I solve a torque problem using a FBD?

To solve a torque problem using a FBD, you first need to identify the object and its axis of rotation. Then, draw a diagram of the object and label all the external forces acting on it. Next, use the equations for torque (T = F x d) and Newton's second law (F = ma) to set up and solve the problem.

4. What are the units of torque?

The SI unit for torque is Newton-meters (Nm). However, torque can also be measured in other units such as pound-feet (lb-ft) or dyne-centimeters (dyn-cm). It is important to use consistent units when solving a torque problem.

5. What are some common sources of error when solving a torque problem using a FBD?

Some common sources of error when solving a torque problem using a FBD include incorrect labeling of forces, not considering all external forces, using incorrect units, and not considering the direction of the forces. It is important to double check all calculations and diagrams to ensure accuracy when solving a torque problem.

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