Chapter 5 – The Laws of Motion
“It’s been quite a break isn’t it ?” asked the old man.
“It does seem to be like it. To be honest, the break between your lessons seems to be around a month.” I answered.
“Then without further ado, let’s continue!”
“Newton’s laws, here I come!”
“Where did we leave last time?”
“I’m talking about Classical Mechanics…”
The old man leaves a heavy sigh and then he continues, “We have discussed the 1st Law of motion by Sir Isaac Newton.”
“Yes I remember now!!!!!” I exclaimed.
“And what did we learn after that ?”
“We learnt friction after that!!!!”
“Now you remember! But do you understand?”
“Sir, What do you mean by that ?”
“Can you give us a recap of the things we have learnt about classical mechanics?”
“Well, I’ll try my best.”I answered in a nervous tone.
I continued, “First, we learned about inertia and then we got to know about the 1st Law of motion which says…”
“You don’t need to have a bookish answer. Take your time and try to say what you have understood.”
I gulped and after a brief pause, continued explaining, “1st Law of motion says that if something is at rest, then it remains at rest and if it is in motion, it remains in motion until a force acts on it.”
“Good. See, you’re not that bad. Don’t ever worry about what people will think. Just be yourself.”
“Ok, I’ll try.”
“And we learned after that?”
“We learned about friction which needs a medium just like sound and it acts opposite to an applied force.”
“Well done. And that’s all we know about classical mechanics for now?”
“The discussion went to quantum mechanics and then it went a bit philosophical.”
“Sorry for that, maybe I’m not that great of a teacher if you want someone a bit textbook-ish”
“No no, I don’t mean that. I really like your way.”
“At least someone understands me. Let’s continue then, shall we?”
“Aye aye, Captain!”
I became eager again to get to know the world and it’s way. However, he went a bit quiet.
Then a sudden unexpected command almost left me in shock. “Keep that phone here.”
I trembled in nervousness and the phone almost fell down from my hands but I somehow kept it on a desk.
He continued, “Good, now give it a little push.”
“Don’t push it with such force that it falls down from the desk, just so that you can create some motion.”
I can do this, I believe in myself. I know I…
“There’s nothing to be nervous about, it’s just a little push.”said the old man.
Without thinking, I gave it a little push and I don’t know whether it was my nervousness or the sudden surge of excitement after getting out of the nervousness, but the push wasn’t a little one at all. I gave my phone such a force that it kept on moving till the edge of the desk and then, the forward motion was no more, because it decided to fall down under another known force discovered by Newton which is called gravity.
I shouted aloud,”Noooooooooooo!!!!!!!!!!!!!!”as it fell down to…
The bag! It is saved by a bag which was already kept there! Just then, I became aware of my surroundings to realize everyone was looking at me in the train due to my loud shout.
But captain to the rescue?
“Dear ladies and gentlemen, what you hear is not just noise, it is a wonder of nature which is called sound caused by the vibrations of the air which reach our ears to cause this effect.”stated the old man.
The people from the train were still staring at us with an intensity which scared the heck out of me!
Old man aka Captain continued,”Now, I know you are wondering how wonderfully amazing are the wonders of nature around us which make our lives wonderful. And you see, Newton’s laws of motion are so important as phonons also move but imagine you are in outer space.”
Now, the people look upwards in awe.
Then Captain said,”In case you don’t know, we can’t listen to sound in outer space so just play deaf!!!”
The people really left us and went back to whatever they were doing. And after the marvelous victory over the crowd, Captain sat down on his chair.
I exclaimed in a low tone to the Captain,”That was Unreal!!!!”
Captain said,”I know lad. But this might be taking a toll on you.”
“It’s ok, this thing is over.”
“No, I mean you have to push again.”
I exclaimed“What?! Are you serious?!”
“Keep quiet, I might not be able to handle it every time. Besides, you don’t have to push your phone.”
“No, you got to push your laptop!”
“This is impossible!!!”
The Captain coughed a few times and like a serious movie dialogue, he stated in a heavy tone, “No, it’s necessary.”
“Ok, I’ll be careful.”
“Well, go for it then!”
I called myself down by the thought that if I get nervous and do something bad, I’ll probably end up getting beaten by the people. So, with all might, in a soft tone I said,”Let’s do this!”
I pushed the laptop but it didn’t fall down. Mission accomplished!
“What did you learn?”asked the old man.
I was again stunned at the sudden question. To be honest, with all of this fuss and with my focus being on pushing the laptop, I almost forgot that I was learning physics.
“Wasn’t it a bit hard to push the laptop to make it fall down?”asked the old man.
After thinking for a while, I answered,”Actually, it did.”
“But you did apply approximately the same force, right?”
“Maybe, I did.”
“Then why did it stay on the desk?”
“Well, maybe because it is more massive.”
“You are absolutely right. Now, can you catch something?”
“I’m pretty good.”
“Good, then toss your phone in the air and catch it.”
“Ok ok, don’t do it with your phone. But you gotta do it with something.”
“I have a ball.”
I know I can’t be helped so I just did it. At first, it was pretty low and then the 2nd catch came from a bit high up in the air.
“What did you feel?”asked the Captain.
“The 2nd toss was a bit difficult to catch.”
“And why is that?”
“Maybe, it got more speed or something.”
“Yes, of course.”
“So what do we learn?”
“When something has more mass and it has more speed, it takes more force to change its state from rest or motion.”
“So, both of them are important?”
“Yes, they are. And the product of mass and speed is called momentum.”
“Woooow, and that is the 2nd Law?”
“Nope. But it is definitely related.”
“Well, the rate of change of momentum is called Force.”
“That’s great except the fact that I didn’t understand what you said.”
“You know, just like the rate of change of displacement is speed and rate of change of speed is acceleration, rate of change of momentum is force which is equal to the product of mass and acceleration.”
“I still got a few questions but I’ll ask them later if you don’t mind.”
“I guess, it’s still too much for a young lad to take in. Then I’ll just end with the 3rd law of motion.”
“No experiments right?”
“You already did that lad.”
“You kept the phone on the desk.”
“The phone must have exerted some force on the desk.”
“Then why didn’t the desk break down?”
“Well, I don’t know. I’m no Newton.”
“It’s because the desk also exerted the same amount of force on the phone.”
“Wait! I think I know this. I have heard about it.”
“To every action, there is an equal and opposite reaction.”
“But it only applies to physics. Don’t try to relate it to your everyday life.”
“So, that’s it for now.”
“But I still got some questions.”
“Ask them then.”
“What is displacement? Acceleration? And…”
“I haven’t told you about this?”
“Oh sorry. It’s my fault. I got swayed away by the laws. I’ll explain them and a bit more about motion and Newton next time.”
“Promise of a Captain!”