FORCES: PUSH AND PULL; CONTACT AND NON-CONTACT; MAGNETISM; GRAVITY, WEIGHT AND UPTHRUST

 This term we have begun learning about FORCES. 

There are two basic forces that make things move or stand still: PUSH and PULL.

 Here you have a very simple video that explains them easily.

We have also learnt that there are two types of forces: CONTACT and NON-CONTACT forces. In the following video you can learn more about forces, work and energy with the help of Dr Binocs. 

We have also studied two non-contact forces: GRAVITY and MAGNETISM.

Magnets are objects that attract or repel other objects that contain iron or steel. Here you have another video by Dr Binocs explaining magnetism

Gravity is a pull force noticeable with very large objects such as planets. Watch the following video to learn more.

The first person to talk about this force was Isaac Newton, a scientist and mathematician that explained many laws in Nature. Here you have a video about him.

Gravity is related to mass and weight. 

We already know that mass is the amount of matter in an object and we measure it in kilograms (kg) or grams (g). But weight is a force that depends  on the mass an object has and also on gravity. Here is the formula:

 

Weight = mass x gravity 

We measure weight in newtons (N). 

I hope this simple video will help you to understand these concepts.

Finally, we are going to talk about a contact force applied by water and air: UPTHRUST. This force pushes objects in air and water up. So it is opposite to gravity.

 The upthrust depends on the mass and the volume the object has that is why some objects float and some others sink. 

An ancient Greek scientist called Archimedes discovered this upthrust force more than 2,000 years ago while having a bath. Here you have a video that explains this easily.