Newton's First Law of Motion: Mass and Inertia

Did you know that if you throw a rock in space, whatever velocity it has at the moment that it leaves your hand, it will continue moving with that velocity indefinitely? That's Newton's first law. It applies to objects on earth as well, it's just that earth's atmosphere complicates matters. Get the full breakdown here!
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Prof Dave I commend your work on Physics alongside all other sciences espcially your diagrams of demostrations . God bless you Sir. I'm a Student of Physics and Astronomy at University of Nigeria

[@ProfessorDaveExplains]

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Really helpful video. Really wish you could correct the tiny mistakes right at the end - the screen behind you uses the word motion when it should be acceleration in a couple of places. Your explanation is all spot on, thank you.

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[@ProfessorDaveExplains]

Awesome congratulations!

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[@deepapanneerselvam4618]

Such an amazing explanation I had ever seen😊😊😊😊🙏you did wonderful job am a civil engineering student but I didn't understand what's inertia.... Mass is a quantitative measurement of an object's inertia wonderful.......

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Great lectures! Fun to see "Viking line" cruise ship in the video, I see them daily irl walking my dogs -they departure from central Stockholm and go via the archipelago to Finland and back :)

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very well explained!!! I was confused about ISS traveling speed of(28,000 kilometers per hour) 😲

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Professor Dave Sir, Yor topics are top-leveled and that's why raising my concern to you. l am studying for "National Eligibility Test" examination, and want to crack up to top rank, I want to clear my basics and then would like to move advance topics. Can you suggest me top books for physics, to gain deep knowledge for Classical Mech., Quantum Mech., Electrodynamics, Mathematical Physics, Atomic Spectra, Thermodynamics, etc? How to increase interest in Physics? I can provide you whole syllabus too, give me some guidance.

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I wasn't really interested in this back wuen my teacher was explaining at but i got perfect scores. Few years have passed and i only remember the 3rd law because i remember teaching it to my classmate. But now, Everything is so much easier to understand that i am interested in it and i see why it's important.

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[@user-lu3wo2qi6d]

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[@norajames2459]

Hi Professor Dave, Thank you for making these videos and educating everyone! I have a question about the ships you were talking about at 3:48. If the cruise ship hits a rock, will it be correct to say the cruise ship will stop, because of the rock's inertia? What happens if the cruise ship's mass was more than the rock's mass? Thank you again for taking the time to create these videos!

[@ProfessorDaveExplains]

i would say that's pretty much accurate! the rock's inertia prevents it from being displaced. if the ship had more mass, that would eventually change, but of course it depends on the specific rock and the specific ship.

[@norajames2459]

Thank you for the reply and help!! :)

[@joevignolor4u949]

@@ProfessorDaveExplains Besides inertia you also need to consider how well the rock is anchored into the sea floor. Using an iceberg instead of a rock provides a cleaner example. When a ship hits an iceberg the two will rebound away from each other. How much each object moves away after the rebound depends on their relative masses, which determines their relative inertias. For the Titanic this was very unfortunate because you also have to consider how much impact damage will occur to each object during the collision.

[@joevignolor4u949]

Newton's first law is often overlooked when discussing rocket propulsion, especially when debunking claims that rockets won't work in space. This is often claimed by people who say rockets won't work in space because they have nothing to "push against". What rockets "push against" in space is the inertial mass of their own propellants. The propellants, as is the case with anything with mass, want to remain at their current velocity due to inertia. Therefore, when a rocket engine accelerates the propellants in one direction against their inertial mass an equal and opposite reaction force is created in the opposite direction to accelerate the rocket.

[@ProfessorDaveExplains]

Very well said!

[@TheIsmaelIsaac]

The enertia means the ultimate absence of ALL forces and since you believe that this true then this contradicts the existence of any gravitational force once the rocket leaves the earth. However you don't believe that and you do believe that the rocket will still be effected by earth's gravity as the rocket going towards the moon and therefore you need propellant force to keep the rocket going towards the moon and not to get pulled down by the small gravitational force of the earth. That's my 50 cents moon landing is a silly narrative

[@joevignolor4u949]

@@TheIsmaelIsaac There is nothing contradictory or silly at all. Inertia is simply a well known physical characteristic of all matter that causes it to remain in a uniform state of motion unless it is acted upon by a force. In the case of a rocket going to the moon it must initially be accelerated by a rocket engine to a high enough speed to get it out of earth's orbit and have it acquire sufficient momentum to coast outbound and at least cross into the moon's gravitational sphere of influence. The initial speed required for this is about 25,000 MPH, which is attained through one single initial rocket burn to break out of earth orbit. Then the vehicle simply coasts outward on its way to the moon using the momentum it acquired during the burn. During the coasting period the earth's gravity does continuously slow it down to where it arrives at the moon traveling only at about 5,000 MPH. Then slowing it down further with an another engine burn it will drop to around 3,000 MPH and place it into lunar orbit.

[@TheIsmaelIsaac]

@@joevignolor4u949 Sorry my friend, you are wrongly assuming after the release of the propeller rocket engines the spacecraft will keep going upward. But this isn't true becuase after the release of propelling rocket you have canceled out one the two forces that were acting upon the rocket which is the thrust force and now the acting force upon the mass (weight) of the spacecraft is the drag down gravity of the earth .. I want you to imagine this, it's like you're driving you car up the hill and sped up 200 mph then you shut off the engine ... what would you imagine is going to happen? Would the car keep going upward or the gravity is going to pull it downwards? There you have it, guys ... That why I was telling you the rocket will not reach the momentum acceleration until all forces aplied upon it are cancelled out. So for apollo to reach the inertia acceleration you must completely cancel out the gravity force that acting upon it. And what goes up must come down, as simple as that.

[@joevignolor4u949]

@@TheIsmaelIsaac If the car is going fast enough and has sufficient upward momentum when you shut off the engine it will continue moving due to its inertia and it will eventually reach the top of the hill. Gravity will slow it down some as it continues upward but it won't stop it immediately. In space its even easier because there is no friction or aerodynamic drag to contend with. In Apollo the third stage of the Saturn V gave the spacecraft sufficient upward momentum to leave earth orbit and continue climbing up and away. Gravity did slow it down as it traveled out to the moon but it still had enough upward momentum to take it to the point in space when the moon's gravity took over and started to pull it down towards the moon. That's how it happened. Its really as simple as that.

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[@Azumanyu]

actual life saver. thank yo u

[@Nightmare_Fog]

Thanks for explaining so well I got 100 on my test

[@mahletthaymanot4059]

Can you make a video about inertia?

[@ariesstar142]

u nailed it

[@yeezzzy7361]

this man is awesome!

[@quawanisongwira4245]

Wow your the best teacher

[@alimenhem8402]

do Fast-moving objects have more inertia than slow-moving objects with the same mass? I noticed that fast-moving objects are harder to stop than slow-moving objects with the same mass. Does velocity affect inertia? I would really appreciate an explanation. thank u

[@yididiya11gaming51]

No, the inertia of an object depends solely on its mass, not its speed. Inertia is the property of an object that resists changes in its state of motion. The equation for inertia (I) is given by: I=m where: I is the inertia, m is the mass of the object. In this equation, mass is the only factor affecting inertia. It doesn't matter how fast or slow the object is moving; as long as the mass remains constant, the inertia remains the same.

[@raniatariq9585]

so inertia is the amount of force needed to move or stop a certain body of mass?

[@costelc4077]

People saying they are here for online school. *Me who discovered this accidentaly.*

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😂👍🏻

[@hazardiangaming189]

XD Same

[@nathanpetay]

yeah i now understand, u're true ilove u're explanation

[@isroindiaofficial7533]

Why is the colour Newton first law of inertia sir

[@methasawijayasuriya6472]

Sir could you please do a video on center of gravity? I just don't get the physical meaning of it. If you have already done a video please send me the link.

[@carultch]

Center of gravity is a weighted average location of all the weight of a body. Such that if you support it at that point, the torques due to gravity of the entire distribution of weight, will add up to zero, and it won't rotate. Support directly above this point, and it won't rotate either. You can find the center of gravity of an irregular shape by hanging it from multiple locations, and drawing a plumb line straight down from the support. Where the plumb lines intersect, is where the center of gravity is located. This term is often used interchangeably with the term center of mass. Center of mass is a weighted average position of all the masses in a body, that ignores the gravitational field as it adds up the terms that define center of mass. Add up mass multiplied by the position vector from a reference point for every individual mass, and then divide by total mass. This turns into an integral for continuous distributions of mass. As long as the gravitational field is uniform, they are interchangeable terms, which is most commonly the case for our purposes on this planet. But center of mass is the concept that is gravity-agnostic, and doesn't depend on the gravitational field. A non-uniform gravitational field would change the center of gravity, but not the center of mass.

[@shilpawadhwa3713]

Good

[@afaanoromoo3569]

What is the SI unit of inertia? Equilibrium is example of Newton's first law or Newton's first law is example of equilibrium?

[@carultch]

Kilograms are the SI unit of inertia. Newton's 1st law is an example of equilibrium, specifically static equilibrium, as there are other kinds of equilibrium (e.g. thermal equilibrium), that are unrelated to Newton's 1st law.

[@gurudevice]

Nice😊

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What is your newest video

[@rishwinray9396]

From malaysia...my teacher sent it the link to see it

[@jacquelinemotomura4902]

Well done professor Dave!!!!

[@boyinathrinay8493]

Sir Dave I am having a fought that for the first question that force is required for ocean only no sir

[@lotfe8606]

👍tank You

[@Prakash-mu9kp]

thank u i was useful video

[@hrushikeshhasabnis8819]

Shouldn't be the object be in Uniform Motion?

[@Knee_Ghast]

i wonder if there is an object on earth that doesn't have friction. But even if it doesn't have friction, The moving object on it will still stop moving due to the force that is pulling objects down (Gravity)

[@comingupforeire7050]

Constant Force is required to overcome the friction

[@joyalpatel6000]

Yeh, basic summary

[@anitalayal9171]

Great

[@YanzMV]

God bless you sir, and may God bless me also with my exams tomorrow :)))

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hi it's one year later, how were your exams?

[@YanzMV]

@@milkbread3237 i passed the subject

[@joyalpatel6000]

@@YanzMV Yay!

[@moinkakar6097]

Is there's a unbalance force which can stop the earth from revolving around the sun?

[@joevignolor4u949]

Theoretically yes. Let's say a large celestial object were to appear from somewhere and enter into the solar system. Let's also say it has the same mass as the earth and is traveling the at the same speed but in the opposite direction. Because both objects are of the same mass and are traveling at the same speed they would both have the same amounts of inertia, but in the opposite direction. Then if they were to collide head on both objects would simply try to stop dead in space. Of course they would also be blown apart by the impact. Because of the collision the remnants would have no orbital velocity so the sun's gravity would easily pull all that material inward and both objects would eventually just disappear into the sun.

[@qwertyqwerty-jy9fc]

I know it's a stupid question but what about the trouble of moving a spaceship close to the speed of light? Is all that trouble just about the velocity close to the earth? Like I do kinda know this, like I know why fuel in dropped when spaceships leave the orbit but like is this it? Is that the whole problem?

[@dogwalker666]

Its to do with energy requied E= mc2 the closer to the speed of light you get you need exponentially more energy to achieve the speed, to achieve light speed would require infinite energy.

[@GeneralCreativeZone]

great work sir .your lecture really help me!

[@rashmisgourmetcooking6714]

nice

[@Anonymous-cq5dl]

Ayyy viking line! Been on that cruise several times

[@hydalaghmani8749]

Can u tell me what was the inertia

[@trnshe2629]

3 years later...inertia is first law of newton

[@mncpearlsciences7479]

I am from India. And this man is really teaching owsm!!! Seriously, never seen a person like him!!!! Bcz of him, breaking a building looks like breaking an egg

[@83jbbentley]

Most cruise ships must cut engines an hour ahead of time before port

[@rkreike]

Q: If inertia is the reason that heavier objects fall slower in a vacuum then expected, then why don’t they fall slower than lighter objects?

[@ProfessorDaveExplains]

inertia is the resistance to acceleration, which is cancelled out by the stronger gravitational attraction. that's why things fall at the same rate in a vacuum. check out my tutorial on newton's law of universal gravitation.

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Op

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He saved my lifeeee!!!

[@jcmjub]

Thank you!!!

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Hey bro there is someone copies your video with no credit

[@ProfessorDaveExplains]

hmmm flag it! and comment to tell them they suck.

[@jannatulnaima4186]

When an object touch water it exert gravitional force..than where the water opposite same force as newton third law?

[@fairyfellermasterstroke]

An object might float or not and it again depends on the mass, except when we have water we usually talk about density, that is mass per volume. So the force will affect water much more than it will affect the denser object falling in, so the water will move out of its way. And it depends on the surface area too, because then there can be more force acting on it. Check out pressure and buoyancy. I hope I didn't forget something of basic importance and I hope you have a nice day

[@fisknylle]

"Most of the universe is in space and very little of it is here on earth" Don't know about you guys, but I think I'm ready for my thesis.

[@frzn1x]

thanks dave

[@kyleengle5332]

Thanks Professor Dave

[@dr.dineshseth9518]

Hello Professor Dave I have a question regarding your inertia Do electrons have inertia

[@ProfessorDaveExplains]

hmm, well i think that anything with mass has inertia, so yes i believe they should!

[@dr.dineshseth9518]

Thank you so much

[@kaushalyaabeygunasekera9588]

Thankyou professor

[@tGoldenPhoenix]

Done.

[@brd8764]

Mass is inertia and anything done to it is change of inertia when the mass is unmoved...

[@Molybed1]

This means that mass is the measure of inertia and that mass itself is not constant (mass changes based upon speed). A bullet fired from a gun probably has more mass than a canonball at rest.

[@ProfessorDaveExplains]

Well, there is certainly such a thing as relativistic mass, but things have to be traveling an appreciable fraction of the speed of light for it to be significant, so it would definitely not apply to a bullet.

[@EducatorSharmin]

Its great video!

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thank you

[@MonkeyCrafter2423]

Thank You professor

[@CaptainBrokenTail]

I swear every time Prof. Dave says "but first..." I expect him to proceed by saying "a word from our sponsors"

[@mahendragupta2896]

5:14 net force zero means no motion i dont think so

[@ProfessorDaveExplains]

for an object at rest.

[@mahendragupta2896]

thanx for replying

[@adrenamcd]

You SAY it correctly in the video. You state that there will be no acceleration, but the text on the screen says there will be no motion. I wish you could fix that. It's a perfect video otherwise!!!

[@johnunderwood-hp8rj]

@@adrenamcd If there is no motion there is certainly no acceleration.

[@adrenamcd]

@john underwood I completely agree with you. Unfortunately, I don’t feel that is made clear in this video, and it is a VERY common misconception with students - they often assume that zero net force automatically means no motion, which is incorrect. I would just prefer it be explained here in a way that would avoid that misconception altogether. Gotta be sure I’m clear, though, that I recommend Professor Dave Explains videos all the time because he is one of the few sources I trust to make clear, easily understood videos!

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wHoS hErE fRoM mR fOwLeR's AsSiGnMeNt

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Me

[@federalbureauofinvestigati2725]

We might go through the wind shield which would be very fun I agree

[@gavinangeloff4746]

I love you Dave

[@mainulhassan3207]

Why you need energy to move object is cool.

[@ashfaqtunio1311]

But why do objects have "inertia"?

[@ProfessorDaveExplains]

it's a property of matter! to get deeper than that we have to talk about higgs bosons and other things i don't really know much about.

[@joevignolor4u949]

@@ProfessorDaveExplains If we could figure that out exactly we probably would also understand gravity as well. Then we could retire and enjoy sitting on a nice beach somewhere letting our mass and corresponding inertia keep us at rest there all day long.

[@dapperblaze2]

Professor dave, I think if you meet someone by the name of TheOdd1out on youtube, also look him up if you dont know him, I think you two would have fun talking about always wearing your seatbelt. :D

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oh ur doing the science work too

[@brytoncaviness3612]

Once I become a jedi I don't need to no the laws of physics because I will defy all of them!!!

[@idk__-_]

that used to be my dream

[@musaddiqmunirliman8267]

1:25 I really thought it was a City