Static Equilibrium and Torque Homework Question

In summary, a hiker weighing 985 N crosses a uniform bridge weighing 3610 N and supported by two concrete supports. The hiker stops one-fifth of the way along the bridge, and the magnitude of the force exerted by the concrete supports on the bridge is 2590 N at the near end and 2010 N at the far end. Using the Static Equilibrium equation, the solution was found by taking the opposite support as the pivot point and expressing the distance from the pivot point of each force in terms of the length of the bridge. The vertical forces were also summed to check the solution.
  • #1
VincentweZu
13
0

Homework Statement



A hiker, who weighs 985 N is strolling through the woods and crosses a small horizontal bridge. the bridge is uniform, weighs 3610 N, and rests on two concrete supports, one at each end. he stops one - fifth of the way along the bridge. What is the magnitude of the force that a concrete support exerts on the bridge:

a) at the near end and
b) at the far end

Answer to a) 2590, b) 2010

Homework Equations



Static Equilibrium: ƩT = 0
T = Frsinθ


The Attempt at a Solution



Took opposite support as pivot point such that Fn x r is the CCW torque where r is the length of bridge
Expressed distance from the pivot point of each force in terms of r
Wrote net torque equation, crossed out r from both sides
Solved for Fn

a) Fn = 985 x 4/5 + 3610 x 1/2
Fn = 2593 N
b) Fn = 985 x 1/5 + 3610 x 1/2
Fn = 2002 N

I am not sure whether or not my approach to this problem is correct.
 
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  • #2
Yes, looks good.
You can also sum the vertical forces - total must be zero - as a check.
2593 rounds to 2590, but I don't see how to get 2010 from 2002.
 

What is static equilibrium and torque?

Static equilibrium refers to the state where an object is at rest and not experiencing any acceleration. Torque is the force that causes an object to rotate around an axis.

What is the formula for calculating torque?

The formula for calculating torque is T = rFsinθ, where T is the torque, r is the distance from the axis of rotation to the point where the force is applied, F is the force applied, and θ is the angle between the force and the lever arm.

How does the center of mass affect static equilibrium?

The center of mass is the point at which the object's mass is evenly distributed. In order for an object to be in static equilibrium, the center of mass must be directly above the support base. If the center of mass is not directly above the support base, the object will topple over.

What are the conditions for static equilibrium?

There are three conditions for static equilibrium: the net force on the object must be zero, the net torque on the object must be zero, and the object must not be accelerating.

How do you solve for unknown forces in a system using static equilibrium and torque?

In order to solve for unknown forces in a system, you must set up equations using the three conditions for static equilibrium and then solve for the unknown forces. It is important to draw a free body diagram and label all forces and distances to accurately set up the equations.

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