Unlike other science subjects taught in school, physics is different in the sense that most students have their own assumptions and ideas about it even before they step in the classroom. As Yoda once said when teaching Luke Skywalker, you must unlearn what you have learned so far to succeed. Despite the fact that it was a science fiction movie, the statement makes sense in the real world and especially to students in Singapore who want to master physics.
One of the simple concepts taught in the first physics lesson is that everything that goes up must come back down due to gravity force. The same force hinders us humans from flying like birds and that objects can be moved if pushed hard enough. The problem is that some of the explanations and ideas are wrong.
Here are some of the common myths and misconceptions about physics that you should know.
1# An Object is Difficult to Push because its Heavy
This is perhaps one of the most common misconceptions because it applies to most of the daily activities. Yes, a heavy object is difficult to push, but that is not because of its weight. The real reason why you find it difficult to move it from point to another is because of its mass or inertia.
What is inertia? Simply put, this is an objects resistance to change in motion. When I was young, I thought is easy to push massive objects when in space, my young self was wrong. These objects still have mass despite being weightless in outer space. Mass of the object represents its inertia.
2# Gravity Enables Planets to Revolve Around the Sun
First, it is important to note that gravity is one of the weakest of the four fundamental forces. It is an attractive force and the main reason why planets are able to revolve around the sun is because they are already spinning in the proto-planetary disk that encircles the sun. The main role of gravity in the revolution is to ensure that the planets remain in orbit around the run, but not pushing the planets along their respective orbital planes.
3# Heavy Objects Fall Faster than Light Objects
This myth was deciphered by Galileo in an experiment where he dropped two objects with varying masses on the Learning Tower of Pisa. The experiment revealed that the two objects fell with the same acceleration.
The main reason why most people believed that heavy objects fall faster than light objects is because they do not factor in another instrumental force that comes into play as the objects fall – air resistance. This force, air resistance, is directly proportional to the area of the object in the direction of motion.
In most cases, air resistance is negligible; however, light objects such as a feather experience more air resistance. This concept was proved by the famous hammer and feather drop experiment that was done on the moon.
4# Outer Space Has No Gravity
Unknown to most people is that gravity is present in outer space; the only difference is that it is weaker than what we experience on planet Earth. That said; it is important to note that astronauts orbiting the Earth do not experience gravity as they are free-falling. The moon, planets, and satellites are all in a constant state of free fall.
They all have a tangential velocity due to their free fall state and this is the reason why they do not crash on what they are orbiting. You should also note that any object in a free fall state becomes weightless.
5# For a Continuous Motion to be achieved there needs to a Continuous Force
This is one of the physics myths that most students find difficult to understand because they do not put into consideration the impact of friction force on the movement of the object. The force that you use to keep the object in motion is only to counteract the frictional force. Picture this, if you threw a hammer in outer space, it would travel at the same/constant velocity forever unless it collides with something. This is based on the fact that outer space is almost empty but has dust and trace elements of gases. As a result, no frictional force would act on the hammer as it moves.
6# The Natural State of All Objects is Rest
In the past, some physics experts believed that everything that moves will eventually come to a stop and rest is the natural state of all objects on planet earth. Even the most famous philosopher Aristotle included this in his Laws of Motion.
We now know that this is just a mere myth as noted by Newton’s First Law of Motion that states “everything at rest will stay at rest, and everything in motion will stay in motion, unless acted upon by an external force.
The first part of this law makes sense and is reasonable, but the second part is a bit tricky and difficult to comprehend because we are not able to identify the specific force that stops motion – friction.
What is friction? This is the force that acts between two objects that are moving relative to each other and are in contact. Whenever you roll a ball on the floor, it eventually comes to a stop due to the friction force between it and the floor.
These are the most common misconceptions about physics that you need to keep in mind as you study physics in Singapore. For the best results, it is recommended to hire an accredited physics tutor to help you understand concepts that you find difficult. Kungfu Physics is the most trusted provider of physics tuition services in Singapore. Get in touch with us for the most comprehensive and tailored physics tuition service in Singapore.