Work, Heat and Energy

Here, we’ll take a closer look at the concepts and ideas of heat, work, and energy.

Heat – Heat is the energy being transferred from hot objects to cold objects.

 

Question 1 of 2

1. Heat is the energy transferred from …

A.
B.
C.
D.

Question 1 of 2

Question 2 of 2

2. A rock sitting at the edge of a cliff has…

A.
B.
C.
D.

Question 2 of 2


 

Next lesson: Precision and accuracy

Video Transcript

It is crucial to understand the basic difference between what is heat and what is temperature.

Temperature – Temperature is intensive property
Heat – Heat is extensive property

You should be recalling that an extensive property (i.e. the mass) is dependent on the amount of a certain substance, whereas an intensive property (i.e. the density) is independent of the quantity.

As a fine example, just look at the difference between boiling a cup holding water in a beaker and boiling 10 liters of water in some other beaker.

Both bodies of water will be boiling at the exactly the same temperature of 100 degrees Celcius but at the same time, we’ll need to heat the 10 liters of water for a far longer period of time. This is because we’ll need to put in much more heat (or energy) into a bigger sample to end up at the same changed temperature (from room temperature up to 100 degrees Celcius).

Work and Energy

Work – Work is the energy required for moving an object against any force.
Work equals Force – distance (W = F – d)

An excellent example of work is when we lift objects against the force of Earth’s gravity. Bear in mind that unless you’re moving an object, you won’t be able to do any work. To give you an example, when you push against a wall or when you spin the tires of your car are actually both situations at which energy is expended. However, there’s no work done.

Energy – Energy is the capacity transfer heat or do work.

To help you better understand the idea and concept of energy, we’re going to take a closer look at these various sorts of energy:

Kinetic and Potential Energy

All energy forms can be divided into these two following main categories:
• Kinetic Energy – This is energy in action – This is the energy of motion
• Potential Energy – This is stored energy – This is the energy of position

Kinetic Energy

An object’s kinetic energy (regardless of whether it is an airplane or an atom) is indicated by this expression:
Ek = -mv2
here, m = mass while v = velocity
The SI unit we use for energy is the Joule (J)
1 Joule = 1 kg-m2/s2

Potential Energy

We speak of potential energy when referring to stored energy. There are quite a few types of potential or stored energy. The chemical energy stored in a battery is a form of potential energy, the elastic energy when you stretch rubber band is potential energy, but the form of potential energy that’s generally referred to physics is gravitational potential energy. Actually, this is energy which is stored thanks to the position of an object. This type of potential energy is dependent on an object’s mass, an object’s height above Earth or the ground, and the object’s acceleration through gravity.

Here are some examples of what we call Potential Energy:

1. When a rock sits at a cliff’s edge, it has potential energy. When the rock falls down, this potential energy is converted into kinetic energy.

2. When a spring in a pinball machine is stretched, it has elastic potential energy. When released, it can move the ball.

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