When I say "work," what first thing comes to mind? Maybe a cubicle? Or a bag? But if you are a physicist, work has a very specific meaning - one that has much to do with spreadsheets or the collapse of the Roman Empire. Today, we're going to explore that definition-- and how it connects to one of the most important principles in physics: energy conservation. We will also learn what physicists mean when they talk about another concept that is far more common in everyday life: energy. So let's get to… work. So far in this study, we have spent most of our time talking about energy, and how it makes things work. And you need to understand power before you understand work. Because work is what happens when you put energy into a certain level, in a system - a system that becomes any category of the universe you use that you are talking about at the moment. For example, if you use a cord to drag a box across the floor, we can say that the box is your system, and the power you use to pull on it with external force.
So, let's say you pull this box system by dragging it straight behind you, so the rope is like the ground. If you use a rope to pull the box by one meter, we can say that you are doing work in the box. And the amount of work you do equals the amount of energy you use to pull the box, the times you move it. For example, if you pull the rope - hence the box - by 50 Newton, while moving it by 5 meters, then we can say that you made 250 meters of the Newton-box box. In general, however, the function is indicated by units known as Joules. Now, sometimes, the energy you put into an object will not be in the exact direction and direction in which the object moves. For example, if you try to drag the box with your hand over the top of the box, so that the string is at an angle. If so, the box would go downhill, but the power would be at an angle. And in that case, you will need to apply the techniques we learned back when we started talking about vectors. Specifically, you have to divide the energy you use into a rope into its own parts: one that goes with the floor, and one that is almost identical.
To find the fraction of the force associated with the ground - that is, the one actually pulling the box forward - you just have to multiply the magnitude of the force by the cosine of the angle of the cable to the ground. You will recall that we typically select an angle in the system as theta. Therefore, to calculate the work done in a box, simply multiply the horizontal object - or F times theta the cosine times - by the distance you removed the box. That's the way scientists often write a work equation - they'll equate it with coercion, distance, times the cosine of theta. And that figure would be equal to any situation that incorporates frequently used energy in a certain range. But what if the power does not last forever? What if, you say, you first pulled Hardon out of the box, but then you started to get tired, so the amount of energy you spent on the box decreased and decreased as you dragged it. To calculate the amount of work you have done in that situation, you will need to calculate the amount of energy you have used in each sub-grade. Therefore, to get a job done with different power, you just have to combine that power according to the distance the object is delivered.
What it will look like. But the range of coercive periods is one of the ways physicists measure work. Because, you know how we just say that Joules is a work unit? Joules are often used as units of something else: energy. And the function uses the same units of power, because the function is just a change of power. What happens when an external force is applied to a system and changes the power of that system. In fact, that is one way to describe power - it is the ability to do work. There are all kinds of energy, but in this case we will mainly talk about two of them: kinetic energy and potential. Kinetic energy is the energy of movement. When the box rested on the floor, we can say that it had no kinetic power. But when you used force and it started to move, it had kinetic energy. And the pressure of the box has changed, which means you have done it. Specifically, the kinetic energy of an object is equal to half its size, multiplied by its square velocity. If this seems normal, that is because it comes from applying Newton's second law and kinematic equation to the idea that the work is equivalent to forcing a period of time. Therefore, if the box weighed 20 pounds [20 kg], and at some point while dragging it, it reached a peak of 4 feet per second, we can say that its kinetic power at that time was 160 Joules.
Then there is the potential for strength, which is not necessarily the same as it sounds. Power can be power and not power-- it may work. In other words, potential energy can be used to perform a task. One common type of gravity is gravity - the basic force that comes from the fact that gravity exists. If I hold the book a meter above the ground, we can say that it has a great gravitational pull. Because if you let it go, gravity will do the work in a book. Gravity releases energy that moves them to the ground. When a book is down, however, we conclude that its gravitational force is zero, because gravity can no longer do the work. Calculating gravity is simple enough: it's just gravity-- - therefore, times the mass of a small object g - multiplied by the length of the object. Or mgh for short. That is, just knowing that the weight of this book is about a pound, and that it is a meter above the earth, can calculate its potential power: 9.8 Joules.
Another type of energy can be energy that reflects the strength of spring. Despite its name, this is not a matter of the year - and yes, I made that joke. Instead, the kind of potential power specified in the springs! The force of the spring is equal to the degree to which it is pressed or extended, the constant times we write as k. This figure is known as Hooke's law, after the British philosopher Robert Hooke, who came up with it in 1660. Now, the continuous, k - also called regular spring - is different for each spring, and is a measure of spring intensity. And the statistics make perfect sense, if you think about it: The more you push in the spring, and the stronger it becomes, the harder it is to resist. You can test this out for yourself by splitting a click pen and playing with the inner spring. By combining Hooke's law, with the idea that work is equal to the range of energy times, we can find energy that can come from spring: twice as much k times the same distance. For example: if you have a spring that has a spring of 200 in Newton per meter, and the block presses it by half a meter, then the potential capacity of the block is 25 Joules. Therefore, when something works in a system, its power changes. But how that power changes depends on the system. Some programs may lose power.
These are known as non-consecutive programs. Now, that doesn't mean that the lost power is literally disappearing into the universe ... And it has nothing to do with the personal politics of the system, either. It simply has to do with one of the basic principles of science: that energy cannot be built up or destroyed. But systems can lose power, such as when a collision from a drag box creates heat. In non-conservative systems, you can still talk about their kinetic power or potential power at any time. But savings programs allow you to do more than that. A conservative plan is one that does not waste energy. Say, a simple pendulum. When the pendulum is high in its depth, it stops moving for a while as it changes direction - meaning its kinetic power, at that moment, is zero. But it has a lot of power, because gravity can work on the pendulum, pulling it down to its depths. Under the swing, that force can be zero, because gravity can no longer pull the pendulum. But now the pendulum has a lot of kinetic energy, because it is passing through. It also turns out that, whenever the pendulum swings are moving, its kinetic forces and forces may be incorporated into the same number.
What if its potential potential increases? Its kinetic power will decrease by exactly the same amount, and vice versa. So now that we can explain the work, we can use that definition to help explain another common term that scientists have a specific meaning of power. Or, more specifically, a medium power. Central power is defined as working overtime, and is measured in Watts, which is one way to say Joules per second. Basically, it is used to measure how much energy is changed from one type to another over time. So, remember that box you were pulling? We found that you made 250 working Joules in a box while moving it 5 meters. If it took you 2 seconds to move the box, then your average power would be 125 Watts. Basically you are a light bulb! Now, we can redefine power in another way, by putting two different facts together: One, that function is equivalent to forcing a period of time. And secondly, that equal velocity is equal to the distance over time. Knowing this, we can say that a force is applied to an object with a certain velocity in the middle. If you move the box by 5 feet in 2 seconds,
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