# Construction Worker Lifting Uniform Beam

• Fetch
In summary, a construction worker attempts to lift a 2.26 m long, 397 N beam off the floor and raise it to a vertical position. At a certain instant, the worker holds one end of the beam at a distance of 1.21 m above the floor by exerting a force on the beam. The magnitude of the force is 168 N and the minimum value of the coefficient of static friction needed for the beam not to slip is 0.35. To find the net force of the floor on the beam, the normal force and the x-component of the push were needed. The correct answer is 255 N.
Fetch

## Homework Statement

A construction worker attempts to lift a uniform beam off the floor and raise it to a vertical position. The beam is 2.26 m long and weighs 397 N. At a certain instant the worker holds the beam momentarily at rest with one end a distance d = 1.21 m above the floor, as shown in the figure, by exerting a force on the beam.(a) What is the magnitude of ? (b) What is the magnitude of the (net) force of the floor on the beam? (c) What is the minimum value the coefficient of static friction between beam and floor can have in order for the beam not to slip at this instant?

## Homework Equations

Just equilibrium conditions. Net force and net torque of the system are both zero.

## The Attempt at a Solution

So I figured out a)168N and c)0.35 but can't find part b

I tried equilibrium conditions for the vertical forces.
W = 397N
F = 168N
N = normal force
theta = 32.37 degrees
W = Fcos(theta) + N
Solving for normal force I got
397N - 141N = 255N

This answer is wrong. What's confusing me is if I use this value for part C to find the coefficient of static friction it works just fine. The answer isn't zero, and even if it was, that would be wrong because the floor pushes back up on the beam due to molecular compression. I don't get why it isn't 255N? Did I miss something here?

Last edited by a moderator:
Fetch said:
Solving for normal force I got
397N - 141N = 255N
That's all correct, but (b) does not ask for the normal force.

Fetch
Yeah I misconstrued the (net) force part. I figured it out now. I needed the normal force (N) and the x-component of the push (F) to find the net force on the beam. My mistake. Thank you.

## 1. How do construction workers lift heavy beams?

Construction workers typically use heavy machinery such as cranes or forklifts to lift heavy beams. They may also use ropes and pulleys to manually hoist the beams into place.

## 2. What type of training do construction workers receive to safely lift heavy beams?

Construction workers receive training in proper lifting techniques, as well as how to operate heavy machinery safely. They also receive training on how to properly secure beams and other materials to prevent accidents.

## 3. Is there a weight limit for construction workers when lifting beams?

Yes, there are weight limits for construction workers when lifting beams. The weight limit will vary depending on the worker's physical capabilities and the specific equipment being used. It is important for workers to follow these weight limits to prevent injury.

## 4. What safety precautions should be taken when lifting beams?

When lifting beams, construction workers should wear appropriate safety gear, such as hard hats and steel-toed boots, and follow proper lifting techniques. They should also ensure that the beams are properly secured and that there are no hazards in the surrounding area.

## 5. Are there any risks involved with lifting beams?

Yes, there are risks involved with lifting beams. These risks include injuries from improper lifting techniques, accidents involving heavy machinery, and potential hazards from unsecured beams. It is important for construction workers to follow safety protocols and receive proper training to minimize these risks.

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