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### How to Calculate the Momentum of Inertia for Different Shapes and Solids

In physics, when you calculate an object’s moment of inertia, you need to consider not only the mass of the object but also how the mass is distributed. For example, if two disks have the same mass but [more…]

### Understanding Heat Conduction and the Factors that Affect It

*Conduction* transfers heat through material directly, through contact. Thanks to physics, we know that conduction is affected by temperature difference, the area of conduction, the distance the heat must [more…]

### Measuring Thermal Conductivity in Different Materials

Different materials (such as glass, steel, copper, and bubble gum) conduct heat at different rates, so the thermal conductivity constant depends on the material in question. Lucky for you, physicists have [more…]

### Transferring Heat through Radiation

Radiation is one way to transfer heat. You experience radiation personally whenever you get out of the shower soaking wet in the dead of winter and bask in the warmth of the heat lamp in your bathroom. [more…]

### Predicting Gas Pressure Using the Ideal Gas Law

In physics, you can use the *ideal gas law* to predict the pressure of an ideal gas if you know how much gas you have, its temperature, and the volume you’ve enclosed it in. [more…]

### Keeping a System at Constant Pressure: The Isobaric Process

In physics, when you have a process where the pressure stays constant, it’s called *isobaric* (*baric* means “pressure”). The first figure shows an example of an isobaric system, where a cylinder with a piston [more…]

### Keeping a System at Constant Volume: The Isochoric Process

In physics, when the pressure in a system changes but the volume is constant, you have what is called an *isochoric* process. An example of this would be a simple closed container, which can’t change its [more…]

### Flowing from Hot to Cold: The Second Law of Thermodynamics

In physics, the *second law of thermodynamics* says that heat flows naturally from an object at a higher temperature to an object at a lower temperature, and heat doesn’t flow in the opposite direction of [more…]

### How to Calculate an Object’s Velocity Based on Its Displacement

In physics, velocity, which is the rate of change of position (or speed in a particular direction), is a vector. Imagine that you just hit a ground ball on the baseball diamond and you’re running along [more…]

### Newton’s First Law: How Inertia Works

In physics, Newton’s laws explain what happens with forces and motion, and his first law states, “An object continues in a state of rest, or in a state of motion at a constant velocity along a straight [more…]

### Newton's Second Law: How Net Force, Mass, and Acceleration Affect Motion

Newton’s first law says that an object remains in uniform motion unless acted on by a net force. When a net force is applied, the object accelerates. Newton’s second law details the relationship between [more…]

### Newton's Third Law: Action and Reaction

Newton’s third law of motion is famous, especially in wrestling and drivers’ ed circles, but you may not recognize it in all its physics glory: “Whenever one body exerts a force on a second body, the second [more…]

### Systems of Measurement in Physics

To keep like measurements together, physicists and mathematicians have grouped them into *measurement systems**.* The most common measurement system you see in introductory physics is the meter-kilogram-second [more…]

### How to Calculate Acceleration

In physics terms, acceleration, *a*, is the amount by which your velocity changes in a given amount of time. Given the initial and final velocities, *v** _{i}* and [more…]

### Understanding Positive and Negative Acceleration

In physics calculations, acceleration — just like displacement and velocity — can be positive or negative. The sign of the acceleration tells you whether you’re speeding up or slowing down [more…]

### How Positive and Negative Acceleration Relate to Speed and Velocity

In physics, the sign of an object’s acceleration depends on its direction. If you slow down to a complete stop in a car, for example, and your original velocity was positive and your final velocity was [more…]

### How to Calculate Time and Distance from Acceleration and Velocity

In a physics equation, given a constant acceleration and the change in velocity of an object, you can figure out both the time involved and the distance traveled. For instance, imagine you’re a drag racer [more…]

### Finding Distance Using Initial Velocity, Time, and Acceleration

In a physics equation, given initial velocity, time, and acceleration, you can find an object’s displacement. Here’s an example: There you are, the Tour de France hero, ready to give a demonstration of [more…]

### What Is a Vector?

In physics, when you have a vector, you have to keep in mind two quantities: its direction and its magnitude. Quantities that have only a magnitude are called [more…]

### Calculating the Resultant Vector of Two Displacement Vectors

In physics, just as you can add two numbers to get a third number, you can add two vectors to get a *resultant* vector. To show that you’re adding two vectors, put the arrows together so that one arrow starts [more…]

### How to Subtract Vectors

You don’t come across vector subtraction very often in physics problems, but it does pop up. To subtract two vectors, you put their feet (or *tails,* the non-pointy parts) together; then draw the resultant [more…]

### How to Add Vectors on a Grid

You can use the components of vectors to add vectors together using a grid. Doing so reduces the problem of adding vectors to a simple combination of adding numbers together, which is very useful when [more…]

### How to Find Vector Components

In physics, when you break a vector into its parts, those parts are called its *components*. For example, in the vector (4, 1), the *x*-axis (horizontal) component is 4, and the [more…]

### How to Calculate the Displacement of an Object Moving in Two Dimensions

In physics, displacement, which is a change in position, has a magnitude and a direction associated with it. When you have a change of position in a particular direction and of a particular distance, these [more…]

### Absolute Zero: The Third Law of Thermodynamics

In physics, absolute zero is considered the lower limit for the temperature of any system, and the third law of thermodynamics can be formulated in terms of this temperature. The [more…]