If you've ever pushed or pulled something, you've used a force! Basically, a force is just that - a push or a pull. But in science, a force is when an object moves because it interacts with another object or field (like electricity or gravity). This movement is called energy, and it's what makes things happen! When we talk about force energy, we're talking about the energy created by the interaction of two objects or fields. So the next time you're playing sports or moving something heavy, remember that you're using force energy to make it happen!

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Forces are not just for pushing or pulling things! There are actually three different things that forces can do. First, they can change the shape of an object - like when you bend, stretch, or compress something. Second, they can change the speed of an object - like when you pedal faster on a or someone gives you a push. This makes the bike go faster! Finally, forces can change the direction of something that's already moving - like when a cricket player hits the ball and the force of the bat changes the ball's path. So next time you're playing a sport or just moving something around, remember that forces can do more than just push and pull - they can change shape, speed, and direction too! And all of these things are powered by force energy.

What is energy?

Energy is the ability to do work, while work is equal to the force being applied to move an object a certain distance in the direction determined by that force. So, energy is how much of the work is applied to the object by that force. The unique thing about energy is that it can be transformed.

Conservation of energy

The conservation of energy states that energy is only transferred from one state to another so that the total energy of a closed system is conserved.

For example, when an object falls, its potential energy is converted to kinetic energy, but the total sum of both energies (the mechanical energy of the system) is the same at every instant during the fall.

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What is a moment?

The turning effect or a force produced around a pivot is called the moment of a force or torque. Examples of pivots are the hinges of an opening door or a nut turned by a spanner. Loosening a tight nut and a door opening around a fixed hinge both involve a moment.

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While this is a rotatory motion around a fixed pivot, there are also other types of turning effects.

What are the types of moments of a force?

Clockwise moment

When a moment or a turning effect of a force about a point produces a clockwise movement, that moment is clockwise. In calculations, we take a clockwise moment as negative.

Anticlockwise moment

Similarly, when a moment or a turning effect of a force about a point produces an anticlockwise movement, that moment is anticlockwise. In calculations, we take an anticlockwise moment as positive.

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How do we calculate a moment of a force?

The turning effect of a force, also known as torque, can be calculated by the formula:

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In this diagram, two forces are acting: F1 and F2. If we want to find the moment of force F1 around pivot point 2 (where force F2 acts), this can be calculated by multiplying F1 by the distance from point 1 to point 2:

However, to calculate the moment of force F2 around pivot point 1 (where force F1 acts), we have to improvise a little. Have a look at Figure 6 below.

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F2 is not perpendicular to the rod. We, therefore, need to find the component of the force F2 that is perpendicular to the line of action of this force.

In this case, the formula becomes F2sin𝜭 (where 𝜭 is the angle between F2 and the horizontal). So, the formula to calculate the torque around the force F2 is:

The principle of moment

Have you ever heard of the principle of moment? It's all about balance! When an object is balanced on a pivot point, the sum of the clockwise moments (or forces) is equal to the sum of the anticlockwise moments. This is what we call equilibrium, and it means that the object won't move unless something changes - like the strength or position of one of the forces. Take a look at the picture below to see what we mean!

See the illustration below:

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Great question! Let's use the principle of moment to calculate the distance from the pivot that the 250N force must be applied to balance the seesaw.

We know that the sum of the clockwise moment must equal the sum of the anticlockwise moment for the seesaw to be balanced. We also know that the force on one end of the seesaw is 750N, with a distance of 2.4m from the pivot.

So, we can set up an equation:

Clockwise moment = Anticlockwise moment

(250N)(x) = (750N)(2.4m)

Here, "x" represents the distance from the pivot that the 250N force must be applied.

Simplifying the equation, we get:

250x = 1800

x = 7.2m

So the answer is that the 250N force must be applied 7.2m away from the pivot for the seesaw to be balanced.

What is a couple?

In physics, a couple is defined as two equal and opposite parallel forces acting on an object at the same distance from the pivot point. The forces are parallel, but in opposite directions, and they create a turning effect or torque on the object.

A common example of a couple is a person turning the steering wheel of a car with both hands. The two hands apply equal and opposite forces to the steering wheel, creating a turning effect that rotates the car's wheels.

One of the defining characteristics of a couple is that the resultant force of the two forces adds up to zero. This means that there is no overall translational movement, only rotational movement. The object will rotate around its pivot point, but it will not move in a straight line.

Couples are an important concept in physics, particularly when studying rotational motion and torque. They are used to explain many phenomena, from the movement of gears in machinery to the behavior of molecules in chemistry.

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To calculate the moment of a couple, we need to multiply either one of the forces by the distance between them. In the case of our example above, the calculation is:

What is the unit of moment of a force?

You're correct that the unit of moment is Newton-meter (Nm), and that torque is a vector quantity with both magnitude and direction.

To calculate the distance from the pivot of a force given its moment, we can use the formula:

moment = force x distance

In this case, we know that the moment of the force is 3 Nm, and the force is 10N. We can rearrange the formula to solve for the distance:

distance = moment / force

Plugging in the values we know, we get:

distance = 3 Nm / 10N

distance = 0.3 m

Therefore, the pivot distance from the line of action of the force is 0.3 meters.

Force Energy

How do you calculate the moment of a force? 

The moment of a force can be calculated by the formula:  T = rfsin(𝜭)

Are moment and moment of a force the same?

Although moment and moment of a force have the same units, mechanically, they are not the same. A moment is a static force, which causes a non-rotational, bending movement under an applied force. A moment of a force, also called torque, is considered to rotate a body around a fixed pivot.

What is a moment of a force called? 

A moment of a force is also called a torque. 

What is the law of moment? 

The law of moment states that, if a body is in equilibrium, meaning that it is at rest and non-rotational, the sum of clockwise moments equals the sum of anticlockwise moments. 

Are moment and energy the same? 

Yes. Energy has a unit of Joule, which is equal to the force of 1 Newton acting on a body through a distance of 1 metre (Nm). This unit is the same as the moment.

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