Forces Project

Presenting My

Forces Project

A primer on forces, vectors and Newton's Laws of Motion.

INDEX

Free Body diagrams

Forces

Vectors

Newton's Laws

Problem-Solving

Some other forces

Work, Power, Energy

Problems

Momentum

11

Some fun

10

Graphs & stuff

We're done!

12

WHAT IS FORCE, ANYWAY?

FORCE IS NOTHING BUT A PUSH OR A PULL ON A BODY!

1. If this sounds a bit too simple for you, think about it! Every single example of force is nothing but essentially a push or pull.
2. You may think there are many different forces, but actually, there are really a few forces in reality! Physicists have identified 4 forces to be fundamental, ie, all other forces are simply combinations of these 4 forces.

VECTORS

Vectors can mean two things. A vector is any quantity that has a magnitude or direction, like a force for example. Diagrammatically, a vector is simply an arrow that denotes magnitude and direction of another quantity on a graph.

+info

FREE BODY DIAGRAMS!

1. A free body diagram is nothing but a diagram where you draw arrows to represent forces acting on a body. That's it. Literally.

SO, TELL ME WHAT I WANT TO KNOW

• HOW DO YOU SOLVE PROBLEMS WITH THIS1? Remember this strategy:
• Read the question carefully, and see what it wants you to do.
• Once you understand the requirements, draw a free-body diagram. ALWAYS DRAW A FREE-BODY DIAGRAM!
• Choose an axis (take one direction of be positive and the other to be negative)
• Now you can use your equations to solve for the unknown.

NEWTON'S LAWS

Physics would have been so much easier if the tree fell on Newton's head instead of the apple.

ANONYMOUS (I love this guy)

NEWTON'S ACTUAL LAWS (VERBATIM)

An object at rest will remain at rest unless acted upon by an external and unbalanced force . An object in motion will remain in motion unless acted upon by an external and unbalanced force"

The alteration of motion is ever proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed

All forces occur in pairs, and these two forces are equal in magnitude and opposite in direction.

NEWTON'S (SIMPLER) THREE LAWS

Every action has an equal & opposite reaction

A body at rest or in contant motion stays at rest unless a force acts upon it.

F=ma

If you apply a force on a body, the body applies the same force back on you. That't how rockets work. You're welcome. The forces don't cancel out because they act on different bodies.

Not really. The real statement is that the net force acting on a body is proportional to the derivative of the momentum of that body.

Or, an inertial body stays in it's state of inertia. Another result is, if a body is at rest, the net force on the body is zero. Example: If I sleep, I will continue sleeping until an external force (my mom) acts upon me.

+info

+info

+info

THE EFFECT OF NEWTON'S FIRST LAW ON TRANSLATIONAL EQUILIBRIUM.

Don't worry. All that long statement really means is that if a body is at rest, Newton's First law states that the net force acting on it is zero. This is very important from an exam perspective.

+info

WHERE DO WE USE NEWTON'S 2ND LAW?

1. Newton's second law is not universal! It can only be applied in the following scenarios.

• The observer is not accelerating
• MASS must always be constant
• The Force should be in Newtons, the mass in kilograms, and the acceleration in m/s^2

+info

FRICTION

A video on Friction

What if there was a world without friction? Let's find out

+info

FRICTION!

Friction is basically the resistance encountered by a moving object when it is in contact with another object (which may or may not be moving). This is due to the unevenness of surfaces on a microscopic level. If I completely polish a surface to eliminate all irregularities, will I eliminate friction?

+info

Dynamic Friction

Static Friction

Occurs when one body out of the two is moving. It is generally much smaller than static friction. Remains (almost) constant with an increase in force applied.

It is a force that tends to keep an object at rest. In other words, the initial friction we face when we try to move an object from rest. Increases as force increases up to a certain limit, where the body starts moving.

VS

VS

+info

Was there anything you feel was not clear, or not explained well enough?

MY TURN!

Each team in a tug of war pulls with equal force on another team. According to Newton’s third law,, what then determines which team wins?

You can hold a block against a rough wall and prevent it from slipping down by pressing hard horizontally.How does the application of horizontal force keep the block from moving vertically because of the gravity?

VS

+info

+info

WORK, POWER AND ENERGY

WORK VS POWER VS ENERGY

Work is the energy transferred when the object moves a distance.

Energy is basically the ability to do work.

Power is the work done per unit time

This is not a satisfying definition. A more technical definition exists, but i's complicated. Basically, energy is what makes things happen, what causes action and motion and change.

Power refers to the work per time an object can do. A "powerful" object can do more work in unit time. That's where we get our general connotation of muscular people being powerful, because they can work more. (This is wrong).

Work is mathematically denoted as the force times the distance travelled. If the force is 0, or if the distance is 0, no work is done. If you study for 5 hours straight without moving, you didn't get any work done!

+info

+info

+info

+info

THE LAW OF CONSERVATION OF ENERGY1

TOTAL ENERGY DOES NOT CHANGE!

1. Total energy does not change, it simply transforms.
2. Energy can change from one form to another during an action, but the total energy remains the same.
3. The total amount of energy is hence conserved.
4. This always holds true, with some slight deviations in experiments.

THE LAW OF CONSERVATION OF MOMENTUM1

Force Distance GRAPHS!.

One of the scariest things in physics (apart from the equations) are graphs. Mechanics uses an obscene amount of graphs. You have already seen the d/t. v/t and a/t graphs, but scientists have come up with another way to torture us students, with an f/d graph These graphs show variation of force with distance in a moving body. It shows you how force changes as a body moves farther & farther away from the starting point..

+info

What situation may this graph represent?

+info

What situation may this graph represent?

+info

What situation may this graph represent?

THANKS!

Lorem ipsum dolor