# Moment calculation with levers

• KINmajor
In summary, Alex is a Kinesiology major and is taking a biomechanics course. She needs help with a problem set involving calculating moments about the axis of rotation. She attached two examples for people to look at. One example involved calculating the moment produced by the force F in each case about the axis of rotation. The other involved calculating the effective force when there is an angle given. Alex was getting help until everyone vanished. She was on the right track, but now she can't remember how.
KINmajor
Hi everyone, my name is Alex. I am a Kinesiology major and taking a biomechanics course which has a lot of physics. I need some help on a problem set involving calculating moments

instructions: calculate the moment produced by the force F in each case about the axis of rotation.

i have attached two examples, hope the drawings are clear enough.

i read the sticky about why no one answers and maybe i needed to show some work to get a response.

for the first one i am pretty sure you just multiply the 39 N by the 1.2 m for an answer of -46.8 (the instructions state the counter clockwise is negative)
again I am not sure if that's correct though.

for the other i honestly don't have any idea, not asking for answers just not even sure how to approach it.

thanks!

Howdy,
There's a kind of standard format to use for asking homework questions. People are helpful, but they want to see some attempted work first. Do you know the formula for the moments? If so, do you see which quantities go into it?

i am a new guy too... lol, but i think i can solve the problem...
but do you consider other forces in the problem?

i don't believe you need to consider other forces (gravity, normal) or anything like that.
this is review and its actually driving me nuts i can't remember how lol.

You posted while I was, so I didn't see. Sorry.
So, does that 39N force tend to cause a CW or CCW rotation?
Look under your keyboard. You seem to have dropped some units of measure.
In the second part, what do you know about calculating the effective force when there is an angle given?

ya i figured our posts overlapped.
i know the it will be a clockwise rotation, but is it really just as simple as multiplying the force and distance?

the angle one i assume i make it into a right triangle and use sin51 = x/275lbs to find the vertical component?

well i was getting help and then everyone vanished?
was i on the right track?

## 1. How do you calculate the moment of a lever?

To calculate the moment of a lever, you need to multiply the force applied to the lever by its distance from the pivot point. This can be represented by the equation M=F*d, where M is the moment, F is the force, and d is the distance from the pivot point.

## 2. Can you explain the concept of a moment arm in lever calculations?

The moment arm is the perpendicular distance from the line of action of the force to the pivot point. It is an important factor in calculating the moment of a lever, as a longer moment arm will result in a greater moment.

## 3. How do you determine the direction of the moment in lever calculations?

The direction of the moment is determined by the direction of the force and the direction of the moment arm. If both are in the same direction, the moment will be positive. If they are in opposite directions, the moment will be negative.

## 4. What is the principle of moments and how does it relate to levers?

The principle of moments states that for a lever to be in equilibrium, the sum of the clockwise moments must be equal to the sum of the counterclockwise moments. This principle is crucial in understanding the balance and stability of levers.

## 5. How can levers be used to increase mechanical advantage?

Levers can be used to increase mechanical advantage by adjusting the distance between the pivot point and the point of application of the force. By increasing the length of the moment arm, the force required to lift an object can be decreased, resulting in a mechanical advantage.

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