Force at point A and E (Static Equilibrium)

In summary, the man is using a stepladder that is in equilibrium state. The sides AC and CE are each 9.0 m long and hinged at C. The bar BD is attached with a rod that is 3.0 m long, halfway up. The man who is climbing 5.0 m along the ladder (AC) is 67 kg in weight. Assume that the floor is frictionless and the mass of the ladder is negligible. Find the forces at points A and E.
  • #1
abcnat
3
0
a man is trying to fix the light bulb at the top of his house ceiling.to reach the bulb,he is using a stepladder that is in equilibrium state.sides AC and CE are each 9.0 m long and hinged at C.Bar BD is attached with a rod that is 3.0 m long,halfway up.The man who is climbing 5.0 m along the ladder (AC) is 67 kg in weight.Assume that the floor is frictionless and the mass of the ladder is negligible.
Find the forces at points A and E.
 
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  • #2
Welcome to PF;
Good question - I take it this is an A-frame ladder?
What have you tried so far?
 
  • #3
yes with bar in the middle. I get 1220.38 N at point A and 928.58 N at point E.I also tried other calculation which i get 129.6 N at point A
 
  • #4
That's neet - so which one is right?
I cannot tell unless you show me your working + your reasoning.
 
  • #5
first draw free body diagram and find angle and stuff so
at point A
9(Fna sin 19.47)=4(mg cos 70.53) + 4.5(Fb cos 19.47)
9(Fna sin 19.47)=875.4 N + 2785.74 N
Fna=1220.38 N

but I'm not sure.the other calculation is pretty much the same but with different angle and get 129.6 N
so what did you get at point A?
overall i did 3 calculations all with different answers.please help me
 
  • #6
Is Fna is the magnitude of the force at point A, normal to side AC
Is Fb the total force at point B?
What happened to the force at point C?
Which angle is 19.47deg?

... I cannot see your reasoning.

Note: you don't need to calculate any angles to do this problem - and your end result will be more accurate if you don't.

eg. let's call the angle ∠ACE is β, then cos(β)=1/3, sin(β)=(√2)/3
Each time you need a cosine of that angle, just write in 1/3.
 
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1. What is the definition of static equilibrium?

Static equilibrium is a state in which an object is at rest and all forces acting on it are balanced, resulting in no net force and no acceleration.

2. How is the force at point A and E calculated in static equilibrium?

The force at point A and E in static equilibrium is calculated using the principle of moments, which states that the sum of the clockwise moments must be equal to the sum of the counterclockwise moments.

3. Can an object be in static equilibrium if it is moving?

No, an object cannot be in static equilibrium if it is moving. Static equilibrium only occurs when an object is at rest.

4. How does the force at point A and E change if the object's weight is increased?

If the object's weight is increased, the force at point A and E will also increase in order to maintain static equilibrium. This is because the increased weight creates an imbalance in the forces acting on the object.

5. What are some real-life examples of static equilibrium?

Some examples of static equilibrium in everyday life include a book resting on a table, a ladder leaning against a wall, and a person standing still on the ground. In each of these cases, the forces acting on the object are balanced, resulting in no movement.

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