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### Calculating with the First Law of Thermodynamics: Conserving Energy

In physics, the *first law of thermodynamics* deals with energy conservation. The law states that internal energy, heat, and work energy are conserved. The initial internal energy in a system, [more…]

### Conserving Energy: The First Law of Thermodynamics

In physics, the *first law of thermodynamics* deals with energy conservation. One of the forms of energy involved is the *internal energy* that resides in the motion of the atoms and molecules [more…]

### Using the Zeroth Law of Thermodynamics: Thermal Equilibrium

In physics, you can apply the zeroth law of thermodynamics to compare the temperatures of multiple objects. Two objects are in *thermal equilibrium* if heat can pass between them but no heat is actually [more…]

### Using the Kinetic Energy Formula to Predict Air Molecule Speed

In physics, you can examine certain properties of molecules of an ideal gas as they zip around. For instance, you can calculate the average kinetic energy [more…]

### How to Calculate Heat Emission from a Blackbody Using the Stefan-Boltzmann Constant

You can use the Stefan-Boltzmann constant to measure the amount of heat that is emitted by a blackbody. Physicists have determined that a blackbody is an object that absorbs 100 percent of the radiant [more…]

### Transferring Heat through Convection: Natural versus Forced

Thanks to physics, we know that convection can be either natural, where heat rises on its own, or forced, where you control the movement of the heat.

You may have heard the maxim “heat rises,” which is [more…]

### Why Temperature Remains Constant during a Phase Change

Thanks to physics, we know that *p**hase changes*occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas [more…]

### How to Measure Volume Expansion Due to Temperature Increase

Thanks to physics, you know that when you increase the temperature of a solid or liquid, its volume will expand. If a solid or liquid undergoes a small temperature change of just a few degrees, you can [more…]

### How to Measure Linear Expansion in a Solid Due to Temperature Increase

When you talk about the expansion of a solid in any one dimension under the influence of heat, you’re talking about *linear expansion.* Thanks to physics, you can measure how much a solid will expand based [more…]

### How to Calculate the Potential and Kinetic Energy in a Spring

In physics, you can examine how much potential and kinetic energy is stored in a spring when you compress or stretch it. The work you do compressing or stretching the spring must go into the energy stored [more…]

### How to Calculate the Angular Frequency of a Mass on a Spring

In physics, you can apply Hooke’s law, along with the concept of simple harmonic motion, to find the angular frequency of a mass on a spring. And because you can relate angular frequency and the mass on [more…]

### How to Calculate a Spring Constant Using Hooke's Law

Any physicist knows that if an object applies a force to a spring, then the spring applies an equal and opposite force to the object. Hooke’s law gives the force a spring exerts on an object attached to [more…]

### How to Calculate Angular Momentum

In physics, you can calculate angular momentum in the same way that you calculate linear momentum — just substitute moment of inertia for mass, and angular velocity for velocity. [more…]

### Calculating Rotational Kinetic Energy on a Ramp

In physics, objects can have both linear and rotational kinetic energy. This can occur when an object rolls down a ramp instead of sliding, as some of its gravitational potential energy goes into its linear [more…]

### How to Calculate Rotational Kinetic Energy

If you put a lot of work into rotating an object, the object starts spinning. And when an object is spinning, all its pieces are moving, which tells a physicist that it has kinetic energy. For spinning [more…]

### How to Calculate Rotational Work

In physics, one major player in the linear-force game is *work*; in equation form, work equals force times distance, or *W* = *Fs*. Work has a rotational analog. To relate a linear force acting for a certain [more…]

### Calculating How Far an Object Will Slide Down an Inclined Surface

You can use physics to calculate how far an object will slide down an inclined surface, such as a ramp. For example, say you and your friends are pushing a refrigerator up a ramp onto a moving van, when [more…]

### How Adding Enough Force Can Overcome Friction

In physics, because of Newton’s third law, whenever you apply a force to an object, say, by pulling it, the object applies an equal and opposite force on you. Here’s an example that lets you work out how [more…]

### Measuring Force and Direction Using Vector Addition

In physics, to take angles (or direction) into account when measuring force, you need to do a little vector addition. Take a look at the following figure. Here, the mass [more…]

### Calculating Equilibrium Where the Net Force on an Object Is Zero

In physics, an object is in *equilibrium* when it has zero acceleration — when the net force acting on it is zero. The object doesn’t actually have to be at rest, as in the example below, which uses a pulley [more…]

### How Gravity Affects the Acceleration of an Object on an Inclined Plane

You can use physics to determine how gravity affects the acceleration of an object as it moves along an inclined plane. When you’re on or near the surface of the Earth, the pull of gravity is constant. [more…]

### Finding the Force of Gravity along an Inclined Plane

You can use physics to determine the force of gravity on an object that moves along an inclined plane. You can break the weight of the object down into components that are parallel to and perpendicular [more…]

### Finding the Velocity of an Object Moving along an Inclined Plane

In physics, you can calculate the velocity of an object as it moves along an inclined plane as long as you know the object’s initial velocity, displacement, and acceleration. Just plug this information [more…]

### How Friction Slows Movement

Friction is an important concept in physics. It’s the force that hinders two materials from sliding past each other. Friction is essential for everyday living. Imagine a world without friction: no way [more…]

### How Friction Relates to Normal Force

According to the laws of physics, the force of friction, *F*_{friction}*,* always acts to oppose the force you apply when you try to move an object. Friction is proportional to the force with which an object [more…]