BrainBox

Balloon Car

MOTION

The state of an object when it is moving from one place to another can be defined as motion. If you were to roll a ball on the floor, it would be an example of motion.

There are many types of motion, such as rotary motion, which is when an object rotates around a fixed object – an example is a wheel. Another type of motion is projectile motion, which is the type of motion when someone throws a ball.

There are three laws of motion which were all published by a renowned scientist named Isaac Newton. These three laws were published around three hundred years ago and are still very important and in use today.

WHO’S NEWTON?

Isaac Newton is a renowned scientist who has published the three laws of motion we mentioned earlier. He was born in the year 1642 and died in the year 1727.

In his life, he wanted to understand the world better, and so he thought that he could describe movements or motion of the universe through mathematical observation. He had his observations published in a book which explained what he understood about the laws of motion. Can you imagine being able to use what we learn in our math class to explain movement around us?

The laws that he published are still used today and help us to see the relationship between an object and a force.

FIRST LAW OF MOTION

The first law of motion is called the law of inertia. Inertia is when something likes to stay the way it is. If something is not moving, it wants to stay still. If something is moving by an outside force, it wants to keep moving.

An outside force is a force that is acting on the object, such as friction on the ground or air resistance such as wind. For example, your bicycle stays at rest with the breaks unless you were to pedal it to get it moving again. If you were to leave a bicycle to travel downhill without anyone pedaling on it, then it would eventually stop because of the friction with the bicycle tires and the grass.

SECOND LAW OF MOTION

Newton’s Second Law describes the direct relationship between the force, mass, and acceleration. This is shown by the equation: F = ma. Acceleration is defined as the change in velocity, which is speed with a direction.

From this equation, we can tell that the greater the mass of the object, the more force it will take to move it. For example, if a toy car weighs 50 grams, in order to achieve an acceleration of 2 m/s^2, 100 Newtons of force needs to be applied. If, instead, we were trying to move a heavy rock weighing 500 grams with an acceleration of 2 m/s^2, we would need 1000 Newtons of force!

THIRD LAW OF MOTION

The Third Law of Motion states that every action has an equal and opposite reaction.

For example, when you push on a wall, the wall also pushes you back. Another example is when a rocket takes off, it releases hot gas downward down so it can move up.

For the project we’re making today, the action is the wind created by the balloon, and the equal and opposite reaction is the car moving!

FRICTION

We mentioned friction when talking about Newton’s First Law, but what is it really?

Friction is “the force resisting the motion of the object on the ground”. In simpler words, friction is the force when two objects are in contact or rub against each other.

Let’s say we’re trying to push a box from one end of a room to another. As you push it, the box will move, but there’s also a force acting in the opposite direction of your push. This force, called friction, will stop the box from moving when you stop pushing it. Another example is when you hit the brakes on your bicycle – the tires and the ground make the bicycle stop with friction.

WHEEL & AXLE

The wheel and axle is a simple machine that has a wheel in the center of the axle and when a force is applied to either one, both parts of the machine moves. The wheel and axle machine helps moving heavy objects. This helps because when you place the heavy object on the axle, the wheels reduce the friction and makes it much simpler to move. We see this machine in many places, for example a wheelbarrow or a car.