# Newton’s Second Law of Motion: F = ma

Professor Dave again, I want to tell you about Newton’s second law. We learned about Newton’s first law of motion, which tells us that an object will continue its state of motion unless acted upon by some net force. The second law continues from there, describing what will happen if some net force is indeed present, whether from internal or external forces. This law tells us that force is equal to mass times acceleration. This is summarized in the following equation, F=ma. What it means is that we can do quantitative calculations relating the magnitude of a force applied to an object, the mass of the object, and the magnitude of the acceleration that object will experience, and it shows the derivation of the Newton as the SI unit of force when we plug in 1 kilogram and one meter per second squared for mass and acceleration. There are a number of things we can say about this equation, which is tiny but powerful. First it means that heavier objects will require the application of greater force in order to achieve the same acceleration as lighter objects, with acceleration being equal to force divided by mass. If we want these objects of varying masses each to accelerate at one meter per second squared, these are the magnitudes of the forces that must be applied in order for the math to work out. This also means that the second law can be rephrased to state that the acceleration an object experiences will be directly proportional to the force applied and inversely proportional to its mass. It is important to note that the net force is the sum of all the forces acting on an object. If multiple forces are acting on an object, which is often the case, we will need to represent them all in a free body diagram and then add up all the vectors to find the net force, which will tell us the direction of the acceleration that will occur in response to the net force. This kind of vector addition allows us to make predictions about the motion of an object even when it is being pushed or pulled in a variety of ways. Since forces are vectors they can be split up into x and y components, which will be useful for doing calculations in certain scenarios that we will investigate later. Newton’s second law of motion has an incredible range of applications, as it can be applied to any force that exists and it describes the motion of all accelerating objects in the universe. We can even use it to do things like calculate the masses of faraway celestial objects, but for right now we will just stick to the basics, so let’s check comprehension. Thanks for watching, guys. Subscribe to my channel for more tutorials, support me on patreon so I can keep making content, and as always, feel free to email me:

## 45 thoughts on “Newton’s Second Law of Motion: F = ma”

• ### TofuTerror Post author

Great video, as always! Straight and to the point.

• ### ScilexGuitar Post author

Best explanations on youtube π YouΒ΄ve helped me a lot in organic chemistry especially π THank you so much

amazing

• ### Lipika Kankaria Post author

this guy deserves way more subscribers .

• ### romeo rovato Post author

very accurate keep it up

• ### CoTubeAk Post author

Hey professor, awesome videos, keep up the good work, thanks a lot for all your hard work, you are helping a first semester college student preparing succinctly for his upcoming organic chemistry exam!! Thanks! I have one question though: do you have any videos on inductive and mesomeric effects? If not would it be possible for you to upload a video regarding these two topics because i don't seem to really get the gist of it and these effects are quite important :/
Anyways thanks again and keep up the good work ;)!

• ### Chimiste Imane Post author

first of all thanks a lot for everything Professor
secondly, can you present to us a video about "fluidization " ? please

Good vid

• ### akruti Mishra Post author

he explains every thing so easily . great explanation

• ### Star Uchiha Post author

well its very cool

• ### Anshul Patil Post author

hey professor!just a little suggestion. can u make vids on stoichiometry

• ### love yourself Post author

thanks a lot professor Dave

• ### Shaunak Lavande Post author

ur a god. Subscribed and liked.

Nice

• ### Jay Jayme Post author

I wanna be Professor Dave in Halloween. He's LYFE. <3

• ### Foxeh Fox Post author

Awesome video. Subscribed and thanks!

• ### Manik Das Post author

Really U r awesome thanks for this…Just one thing please elaborate this topics more

Super

• ### Persik II Post author

Can please someone help explain how we got 26kg. Because I have multiplied 20 to 0.77 and the result was 15.4

• ### rudy H. Post author

my teacher complicated this but you just showed me that itβs easy, give her teaching lessons please x

• ### Chocolates Xu Post author

I HATE STAAR TESTS

• ### Alex Post author

professer dave again , luv the vids

• ### Ethan Ingram Post author

professor dave again

• ### Jonathan Cipriano Post author

thank you physics jesus

• ### Drapple Animations Post author

it wouldnt be heavier object because we are talking about mass

• ### wyskun Post author

I have a very important 2 questions for me:)

1. In space, there is a space shuttle that does't move. Mass of this shuttle is always constant. This space shuttle has a rocket engine which produce a constant force of 100N. When the engine is started and the ship has a constant thrust of 100N, when the ship starts to accelerate, will the acceleration be constant and remain constant (let's assume 10m / s), or maybe the acceleration will start to decrease as the speed increases? It is related to the rule Ek = 1 / 2mv ^ 2 ???

2. Same space shuttle doesnt move. Shuttle start to accelerate from 0km/h to 10km/h in 5 seconds and it takes "X" energy for example. How much energy it will needed to accelerate also 10km/h more in also in 5 seconds when it allready have velocity of 100km/h ? Also "X" energy? Or much more "X" of energy? And why is that?

• ### Eswar Chava Post author

Sir plse tell about fundamental forces of nature

• ### Dr.Dinesh Seth Post author

Hey Prof
Does Force applied also depend on the shape of the body as you take a toy car and push it, it will go a distance "x" and invert it and check and push it with the same force it will go less distance . Thus the shape also comes in picture

Now I remember why I don't enjoy learning physics.
I enjoy knowing and understanding physics but learning it is painful.

• ### Seema Bahir Post author

If no acceleration is there and only constant velocity then how to we calculate force.

• ### Burn My Uncle Post author

Checking comprehension, I am a newbie, donβt know much about physics, but when I tried, the mass of the cart is…… about 26 kg wtf what did I do wrong, then it turns out that I wished to push a huge ass cart lol. Not what I imagined

• ### Ibitoru Cookey-Gam Post author

This guy is better than crashcourse

• ### xkitox Post author

Why is it meters per second squared and not just meters per second?

• ### Gupsy Ghai Post author

What is free body diagram

• ### Nobuhle Dube Post author

i like this guy

• ### Sanauj15 Post author

In your example at the end you took velocity to be equal to acceleration. Are they supposed to be different though?

• ### yara saeed Post author

as an Egyptian girl I really really like your video…you're intelligent Dave!β₯

• ### jap libatique Post author

. ok i didn't get his answer

• ### Anders Ferrell Post author

I think you have dyslexia

• ### Ceyni Cayuuni Post author

good gooog goog

• ### Abbas Abdallah Post author

THANKS MAN AMAZING VIDEO YEEEEEEAEEAAAHAHHAHHHHHHHHHH!!!1!1!1 BOWWWLINGGGGGG BUNDALONG 4 LIFE

• ### Vlog with anna Post author

Awesome teaching sir

• ### ABD EL-KHALEK MAHMOUD Post author

a stone of mass 5kg falls from the top of a cliff 50m high and buries 1m in deep in sand.find average resistant offered by sand (the answer in the book is 2450N) and if i use the equation (mg-Fres=ma) the answer i get is 2499N COULD YOU EXPLAIN THIS PLEASE

• ### Image Poudel Post author

sir plz prove that e=mc square

• ### Oddgeir Post author

Mass of the cart is irrelevant because I'm strong. πͺ