Friendly Physics

So what is a force?

A force is really just a push or a pull on an object. It occurs when two objects interact with each other. Forces can be contact forces, meaning that the objects have to actually touch. Or they can be at a distance, think along the lines of magnets or gravity. A force is still present but the objects are at a distance.

It helps most to think about forces in terms of balance. You might hear the terms balanced or unbalanced forces...

Let’s forget the math today and focus on Newton’s Laws.

Newton was a mathematician and physicist born in the 1600s. He existed, taught and studied well before many of our modern discoveries had been made, but his impacts are still felt today. Most importantly, for us, in this Laws of Motion.

There are 3 Laws of Motion. All have to do with force and how an object experiences force.

The First Law is commonly referred to as the Law of Inertia...

However, we don’t always just move objects at a parallel to the ground. More often than not, we move them at an angle. Think about your field goal kickers on a football field or a missile being launched. These objects move up, peak and then come down.

We say that they follow a trajectory. They exhibit parabolic motion. The objects peak and then they fall. They are projectiles.

There are many important things about this motion. First, lets focus on that angled launch...

I promised an exciting episode that would take us into a whole new dimension.

Let’s start talking projectile motion → the movement of objects that break beyond just one dimension and instead travel both horizontally and vertically.

We are going to discuss objects that move down and sideways today. It is the easiest way to begin talking about projectiles.

Imagine a cannon on the top of a cliff, shooting a cannon ball out...

The past few weeks we have moved on from talking about objects moving horizontally, back and forth, and started to talk about objects that move vertically, up and down

We started off by thinking about objects that fall, like an apple from a tree or a book off a shelf...

An important thing to keep in mind as we discuss upward vertical motion → we are talking about objects launching straight up into the air. Ideally, without wind or disproportionate weight or any other factors, an object launched upward from the ground would move in a straight line. That is the type of motion we are dealing with here.

Two weeks ago we added an element to our motion repertoire: vertical motion...

Last week we listened to the start of a new idea. We expanded on motion and are now talking about up and down → vertical motion.

We spent a lot of time getting accustomed to objects moving - where they are, how fast they move, what direction that movement is in

And now we’re applying it to objects that are withstanding the force of gravity.

Last week I gave you two equations → the first one was simple. It says v is equal to Vo (initial velocity) + a times t...

We are going to spend the next episodes talking about TWO dimensional motion. UP & left, down & right. We are adding a whole new dimension to motion

Before we do that,

We are going to check off one more type of one dimensional motion → vertical motion. Motion that is UP or DOWN.

When we start to talk about vertical motion we have to worry about gravity.

If you throw a ball up into the air, what happens? It goes up and up, but eventually it comes back down...

We are wrapping up one dimensional motion today with all of the key ideas covered. We’ve talked about distance and displacement, speed and velocity and last week we talked about acceleration as the rate of change of the velocity over time.

We talked about how positive acceleration means the velocity is increasing, the object is speeding up, and negative acceleration means the velocity is decreasing, the object is slowing down.

And then, I left you with a few challenge questions.....

Let’s get to it.

Acceleration is the rate of change of an object's velocity. It is how the velocity changes. When car companies brag about how quickly their vehicles go from 0 to 60, they are talking about the acceleration.

They are talking about how quickly their car's velocity can change from 0 mph to 60 mph.

Objects don’t just stay at a constant velocity, always moving at 2 m/s. They speed up and slow down...