Calculating Forces Acting on a 50m Bridge with Two Supports: A Torque Question

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In summary, the conversation discusses a problem involving a 50 meter bridge with two supports and a mass of 80000kg. A truck of 30000kg is positioned 15m from one of the supports, and the question is asking for the forces acting on the ends of the bridge. The answers provided in the back are F_a (support closer to truck): 598000N and F_b: 480000N. The conversation also includes equations for torque and center of mass, and the attempt at a solution involves finding the sum of forces and torque at point A. The person asking for help is unsure of their solution and is seeking assistance.
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Homework Statement


http://imgur.com/BqIoe

There is a 50 meter bridge with two supports. The bridge has a mass of 80000kg. A truck of 30000 kg is 15m from one of the supports. What are the forces acting on the ends of the bridge?

Answers in back are F_a(support closer to truck): 598000 N and F_b: 480000 N

Homework Equations


torque = Force_perpendicular * distance

center of mass for uniform object is center of geometry

The Attempt at a Solution


Sum of Forces in y direction on bridge: = -80000g - 30000g + Fn A + Fn B = 0

Torque @ A = -15(30000) - 25(80000) + 50*Fn B = 0
Fn B = 490000

Torque @ A = 35(30000) + 25(80000) - 50*Fn A = 0
Fn A = 305000

What am I doing wrong? Any help is appreciated.
 
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Related to Calculating Forces Acting on a 50m Bridge with Two Supports: A Torque Question

1. What is torque?

Torque is a measure of the twisting force applied to an object. It is typically measured in units of Newton-meters (N·m) or foot-pounds (ft·lb).

2. How is torque calculated?

Torque is calculated by multiplying the force applied to an object by the distance from the point of rotation to the point where the force is applied. The formula for torque is: Torque = Force x Distance.

3. What is the difference between torque and power?

Torque is a measure of the force that causes an object to rotate, while power is a measure of how quickly work is being done. Torque and power are related, but torque alone does not determine the speed of rotation.

4. What are some common units of torque?

Some common units of torque include Newton-meters (N·m), foot-pounds (ft·lb), and pound-feet (lb·ft). Other units such as kilogram-force meters (kgf·m) and inch-pounds (in·lb) may also be used.

5. How is torque used in everyday life?

Torque is used in many everyday activities, such as turning a doorknob, riding a bike, or opening a jar. It is also an important concept in engineering and physics, and is used in the design and operation of machines and vehicles.

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