welcome to another video today we're going to be going through the topic of mass and weight so here are a few things that we want to cover today and we'll begin the video just have a quick read through that first so the first question is what is mass mass is just defined as the amount of matter that makes up an object and matter is pretty much just the stuff that makes up the universe so anything that occupies space and has mass is considered matter which is pretty much just the building blocks of you know everything in the universe so mass is measured in the units of kilograms which we should be fairly familiar with um and the interesting concept here is that all masses have something called inertia which is pretty much defined as the resistance to change in motion for something to be still and suddenly move and or something for for for something that is already moving to suddenly come to a stop um for every object that has mass they will have some level of resistance to it for changing in in its motion and the larger the mass the larger the inertia is so for example you might think of like a really really heavy truck that is standing still and if you suddenly want to get that truck to move it's going to take uh quite a bit of effort to to do so because they've got a high level of inertia and same thing as uh a truck that is moving at a really really high speed and for it to suddenly stop it's gonna it's gonna take a lot of effort to make that truck stop because it's got a high level of inertia that's why it's so dangerous sometimes when a truck is you know traveling at a really really high speed on a highway or something and uh you know for it to suddenly stop it's it's pretty difficult so it's uh the truck gets carried forward even after the truck driver might push on the brakes um and that's all due to inertia uh you know higher the mass the higher the resistance to changing in motion um so that's important now oppositely for something that weighs much less well in fact something that has much less mass um then they've got a lower level of inertia so you know if you think of uh a small little insect like an ant or something then for it to go from zero speed to high speed it will take much less effort than that truck that we talked about and same scenario with uh you know and say already in motion and you suddenly want it to stop well that's not gonna take that much effort uh compared to the example of the truck that we talked about before so that's that's inertia um now how is mass different from weight well you know mass and weight is commonly used uh you know in in the same terms in common english but it's actually not the same in the realm of physics weight is actually uh considered what we call the force on a mass and due to gravity and the gravity on earth is always constant at 10 meters uh per second per second which is this unit over here and so the formula for weight is weight which is capital w is equal to the mass of the object times the gravitational pull which is 10 as i said before um so for example if you had person a right that has a mass of say 60 kilograms then the weight which is actually the force would be 60 times 10 okay so that's the gravity which is constant um and so what you would get would be 600 newtons and it's a newton's because weight is a force okay now you might want to compare that to person b for instance that might have a mass of say 80 kilograms and so the weight of this person would be 80 times 10. which is 800 newtons right so very important fundamental difference between mass and weight remember weight is the force that is applied to the mass mass is pretty much just the amount of matter of that object or person okay so um in the next video we'll be talking taking a look at uh density this was a fairly short video just to demonstrate the difference between mass and weight and also the concept of inertia as well um so i hope you found the video helpful and in the next video we'll take a look at density thank you very much