# Friction and torque of ladder resting on wall

• SA32
In summary, the problem involves a uniform ladder with two forces acting on it: the weight of the do-it-yourself enthusiast and the weight of the ladder itself. The ladder is placed against a smooth wall and rests on the ground with a frictional force acting on it. To sum the torques around the point where the ladder touches the wall, we need to consider the vertical distance for vertical forces (such as weight and normal force) and the horizontal distance for horizontal forces (such as friction). This will result in a torque equation of -m1g(L-d)cos(x)-(m2g)(L/2)(cos(x))-fLsin(x)+N2Lcos(x).
SA32

## Homework Statement

Sum the torques given in the problem about the point at which the ladder touches the wall.

## Homework Equations

T(torque)=F*d

See attachment for diagram.

## The Attempt at a Solution

-m1g(L-d)cos(x)-(m2g)(L/2)(cos(x))-fLsin(x)+N2Lcos(x)

I know that torque is the force multiplied by the distance to the pivot point. What I don't get is why we are only concerned with with each force's vertical distance from the pivot point and not the horizontal distance. Help, please?

#### Attachments

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SA32 said:
I know that torque is the force multiplied by the distance to the pivot point.
Actually, torque is the force multiplied by the perpendicular distance to the pivot point--direction matters!
What I don't get is why we are only concerned with with each force's vertical distance from the pivot point and not the horizontal distance.
Since it's the perpendicular distance that counts: for vertical forces (like weight and normal force), it's the horizontal distance; but for horizontal forces (like friction), it's the vertical distance.

Ahh, that makes sense. Thanks!

## 1. What is friction and torque?

Friction is the force that opposes motion between two objects that are in contact. Torque is the twisting force that causes rotation.

## 2. How does friction and torque affect a ladder resting on a wall?

Friction between the ladder and the wall helps to keep the ladder in place and prevents it from sliding down. Torque is responsible for keeping the ladder stable and preventing it from tipping over.

## 3. What factors affect the friction and torque of a ladder resting on a wall?

The weight of the ladder, the angle at which it is leaning against the wall, and the coefficient of friction between the ladder and the wall are all factors that affect the friction and torque of the ladder.

## 4. How can I calculate the friction and torque of a ladder resting on a wall?

To calculate the friction, you will need to know the coefficient of friction between the ladder and the wall, and the weight of the ladder. To calculate the torque, you will need to know the distance between the base of the ladder and the point of contact with the wall, and the weight of the ladder.

## 5. How can I increase the friction and torque of a ladder resting on a wall?

To increase the friction, you can use materials with a higher coefficient of friction, such as rubber or sandpaper, between the ladder and the wall. To increase the torque, you can increase the weight of the ladder or decrease the distance between the base of the ladder and the point of contact with the wall.

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