Newtons Laws of Motion

Have you ever noticed that is harder to start pedaling your bicycle than it is to ride at a constant speed? Or wondered what causes bicycle to move? Or ever thought what is the reason it goes forward instead of going side-wards or backwards?
These questions were not answer till the 17th century till Isaac Newton described the fundamental laws of motion.
So what Newton understood that the things keep on doing the same thing they are doing. So when your bicycle stopped, it stays stopped, and when it is going, it stays going.

Objects in motion tend to stay in motion and objects at rest tend o stay at rest.

This is Newton's first law of motion. Physicists call it the law  of inertia which is the fancy way of calling it that moving objects don't spontaneously speed up, slow down or change the direction. It is the inertia that your must over come to get your bicycle moving.

Now you know that you need to overcome the inertia to get your bicycle moving. But what is that, that allows you to overcome it? This would be answered in Newton's second law of motion.
In mathematical terms newton's second law says-

  Force= Mass*Acceleration

 To cause an object to accelerate, or speed up,  a force must be applied. The more force you apply more it accelerate. And the more mass your bicycle has, and the more mass you have too, the more force you have have to use to accelerate at the same rate. This is why it would be very difficult to pedal a bicycle having 100 kg. of weight. And this the force applied by your legs by pushing the pedal which is the force used o overcome inertia.
This was Newton's second law of motion.
Now the final question. When you do get your bicycle moving why does it go forward?
According to Newton's Third law of motion

For every action, there is a equal and opposite  reaction. 

To understand this, think about what happens when you drop a bouncy ball as the bouncy ball hits the floor, it causes a downward force on the floor. This is the action. The floor reacts by pushing on the ball with the same force, but in opposite direction, causing it to bounce back to you. Together what the ball and floor form is called the action reaction pair. When it comes to your bicycle, it is a little more complicated. As your bicycle wheel spins clockwise, the parts of each tire touching the ground push backward against the earth: the action, the ground pushes forward which is the reaction.
So this was the Newton's third law of motion.

Hope I was a good physics teacher.





Credits: https://www.youtube.com/watch?v=JGO_zDWmkvk