Push and Pull
We are surrounded with forces everywhere we go and in almost everything that we do. Gravity is a force that keeps us on the earth. Friction is a force that heats things up. This happens when we rub our hands together and the heat that is generated from the friction makes our hands warmer. Pushing and pulling is making use of another force as well as pressure, which is force applied by an amount of weight.
An Example of push as a force would be to push on a swing. The force moves the swing in a particular direction and the harder that you push the further the swing will go.
- An example of pull as a force would be opening a door. If you pull on it lightly, the door won’t open, but if you pull with greater strength, the door opens enough. If you pull the door too hard it will slam into the wall.
- An example of pressure as a force is when you push down on a pile of grapes. The weight squashes them. When you walk outside on a snowy day, the pressure of your weight leaves footprints in the snow.
One of the first scientists to study force and gravity was Isaac Newton. He created three laws that are still in use today and they are called ‘Newton’s 3 laws of motion’:
- A body in motion is likely to stay in motion, whereas a body that is at rest will stay at rest. An example of this would be someone who is sitting on the floor watching television. They will continue to do this unless a motion is put into play to change it. Whereas a kid playing outside is moving around and will continue unless something happens to stop it.
- If a force acts upon a body, it will change the body’s direction or speed. An example of this would be to run up to a soccer ball and kick it. Your foot changed both the direction and speed of the ball.
- For every force and action, there is an equal reaction. The same example of the soccer ball can be used. A small kick won’t move it very much but a big kick will send it to the other side of the field.
Any kind or type of force actually breaks down to being just a pull or push.
Another type of force is magnetism that may pull an object toward it or push it away, depending upon the polar fields.
Inertia is not considered a type of force. Anything that has mass or weight will automatically slow down due to the weight. This is inertia. Objects that are larger have more inertia and with increased inertia, the greater the force that is needed to make it move. An example might be to compare a caterpillar with an elephant. The elephant has more inertia.
Elastic and springs are also types of force. When you push against them they will resist however they will spring back with the same amount of force that you inserted on them. If you want to watch this in action you can get the child’s toy ‘Slinky’ and place it at the top of the stairs. When you press and send it down the stairs the force continually contracts and expands so that it ‘walks’ down the stairs. The compression and contraction are equal to the same amount of force that you originally exerted on it. It is also an example of the push and pull force that is happening between the springs.