Why Forces are a Force to be Reckoned With

Why Forces are a Force to be Reckoned With
 
You don’t have to be a high school science student to realise that forces play an important role in our everyday lives. Picking up your suitcase requires force – and you have to exert more force when that suitcase is full of textbooks. There are forces at work on everything in the universe, from large objects right down to the tiny atoms that make up those objects. With that in mind, here’s what you should know about forces:
 
Defining Forces
A force is something that causes a change in an object, like a push or pull and it can affect an object in three ways:
 

• It can cause a change in the shape of the object.
• It can cause an object at rest to start moving.
• It can cause a moving object to change direction.

 
Forces may be classified as contact or non-contact. A contact force is one where the force makes contact with the object it’s affecting, such as the wind causing a flag to wave. A non-contact force is one where the force doesn’t touch the object at all but still affects it like gravity, electricity and magnetism.
 
Forces are measured in Newton’s (N), named after Sir Isaac Newton who was the first to define the concept. You should also remember that Force is a vector quantity which means it has both magnitude and direction.
 
Understanding the Different Forces
All physics students will need to learn about the different forces and how they affect an object. Your high school science teacher will go into more detail about these forces, but for now, imagine your science textbook on top of a table. At this point, there are two forces at work; gravity is pulling the book towards the floor and, the table is exerting a force on the book in the opposite direction to gravity. We call the force exerted by the table, the Normal Force and the normal force is always perpendicular (or at a right angle) to the object.

Oblique Forces or Forces at an Angle
If you recall when we introduced the Normal Force, we mentioned that it is always perpendicular to the object. But what would happen if a force was applied to an object at an angle? Think about what would happen if you took your dog for a walk and you had to tug on the lead to get him to move. In this case, the force you’re exerting would be at an angle to the object (or dog) you’re trying to move and so there are two components to the force; one is horizontal and the other is vertical.



When working out how much force is exerted either horizontally or vertically, trigonometric functions must be used. Provided you know the total force and the angle of one of the vectors, you can use a simple Sine or Cosine calculation to work out the forces.
 
Forces working against an incline works differently. Picture what would happen to your textbook if you lifted one side of the table up. Would it start sliding towards the opposite edge? It might move or might not, and this is an example of a force called Friction.
 
If your textbook stays in the same place, then it’s due to Static Friction. You’d have to apply more force to overcome the static friction that holds the book in place. Let’s say your textbook goes sliding off the edge of the table and falls to the floor. Then this is due to Kinetic Friction, which is the force between two objects that are moving against each other. Both types of friction are essential for driving a car as you need to use more force (or accelerate) to overcome to static friction resulting from the grip of the rubber wheels on the road, and you have to brake (which increases the kinetic friction) to bring the car to a stop.


F_⁄⁄  and F_W are perpendicular to each other.  F_g and F_⁄⁄ will both contribute to the sliding force of the object. F_W and F_⁄⁄  will be calculated by means of trigonometric ratios.

Subatomic Level
Forces don’t only act on large objects such as textbooks and dogs; they also affect the smallest particles in the universe – those that can’t be seen with the naked eye. The study of forces at this level is part of a branch of study called Quantum Mechanics.
 
Two of the non-contact forces we mentioned earlier affect small particles of matter; electromagnetism and gravity. Then there are two other forces known as Weak Nuclear Force and Strong Nuclear Force.
 
Conclusion
Whether you see them or not, forces are at work around us every day. If you can understand and work out how a force affects an object, you can predict how it will behave. From a textbook sliding off a table right down to the smallest atom, forces move our world and that makes them a force to be reckoned with.
 
Want to learn more? Our FREE downloadable worksheets are a great place to start. Click here to find worksheets for Maths & Science from Grade 1 to Grade 12. Or get in touch with us to find out more.




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