What is physics and why is it important?

Physics is the study of the relationship between matter & energy. Physics is able to describe the world through math.

Physicists are able to learn through experiments where they take a guess called a hypothesis. They use the results to create a theory that helps explain their experiments. 

Some important theories of physics are the laws of motion. Newton's First Law of Motion is an object will stay stopped or it will keep on going unless it is interrupted by a force.

A force is not the same force a small green creature uses. A force is a push or pull on an object.

An example of Newton 1st Law is a soccer ball will stay still unless it is kicked. 

Newton's Second Law explains that to make something move one must apply force.

For instance, a box must be pushed or pulled to move. 

Newton's Third Law shows that every action has an equal and opposite reaction. This means that every force applied to anything has an equal force opposite to it.

Like how a bouncy ball bounces back up when thrown on the ground or when you a kid pushes forward on a skateboard and the kid moves.

Sometimes the force a single human can put out is not enough. Like pushing a really heavy box can be hard. However, if you put wheels on the box, it becomes much easier to push. This is the idea of the six simple machines which are mechanisms that multiply force.

The six simple machines are the inclined plane, wedge, pulley, lever, screw, and wheel and axel. Everyone uses these to do tasks easier. A water bottle lid uses the screw, cutting vegetables with a knife uses the wedge, and many more.

Just like the laws of motion, gravity is an important idea of physics. Gravity affects everyone every day, but what exactly is gravity? Gravity is a force of attraction that brings two or more objects towards each other.

Accidentally dropping that orange juice on the floor? Who's faut is that?

Gravity.

Pouring some orange juice into a cup? How does it go straight to the bottom of the cup?

Gravity.

Throwing a ball? How does it come back down? 

Gravity.

Gravity is involved in everyday life.

The gravity on different planets can be very different from that of Earth. 

On the moon the force of gravity is very light, so objects will not fall to the ground as fast. On the other hand, Jupiter's gravity is almost three times that of Earth. If one was able to stand on Jupiter, the gravity will be heavy on the body.

Gravity affects a person's weight, but not their mass. Mass is how much matter is in an object while weight is the mass times the gravity. Mass will always be the same, but weight can be different on different planets. So, someone on a scale on  Mars may be lighter than a scale on Earth.

When an object is dropped, gravity makes all objects drop at the same speed. (Without air resistance). So any two objects will hit the ground at the same time.

This is when an object experiences free fall.

However, in the real world, there is air resistance. Air resistance is the force from the air that goes in the opposite direction of the wind. Air resistance can be shown by dropping a floating piece of paper or someone skydiving with a parachute.

Another way air resistance can be seen through airplanes to which the lift is greater than the air resistance. The wings on an airplane are made to make the air move faster on top which decreases the pressure and allows the airplane to fly. This is called lift.

Another important idea of physics is inertia. Inertia is very similar to Newton's first law where an object wants to stay in the same position. People can "feel" inertia in multiple ways.  Many can feel it in a car, elevator, and a bike.

Why do drivers lean forward when braking? 

Inertia.

Why is it hard to pedal a bike in the beginning?

Inertia.

What is that weird feeling when an elevator first moves?

Inertia.

All the answers are inertia because the object has to change from not moving to moving or vice versa in the beginning. Like when riding a bike the biker first has to push hard on the pedal to "break away' from the inertia of the bike wanting to stay still.