SPH3U1 - Unit 3: Energy and Society

Mechanical Work (W)

The force applied to a displaced object in the direction of the force.

• Scalar Quantity

• SI Units: Joules

W = F∆d

Mechanical Work /w vertical and horizontal components.

W_v = F_Acos(ø)∆d

W_H = F_Asin(ø)∆d

What is the work of objects with 0 displacement

It will always be 0 J because there is no displacement, and no matter the force applied, it will be multiplied by 0.

Positive and Negative Work

There are 2 forces acting on an object, meaning we must calculate for both (F_A and F_f)

• Friction Force will always be negative if it is acting in the opposite direction as the force applied.

W_net = W_A + W_F

Graphing Work as a constant and uniformly increasing variable

Constant:

Uniformly Increasing:

Energy

The capacity/ability to do work

• 2 Main Types:

  • Kinetic Energy (E_k)

  • Gravitational Potential Energy (E_g)

Kinetic Energy

The energy possessed by moving objects

Work-Energy Principle

The net amount of mechanical wok done on an object is equal to the object’s change in Kinetic Energy

• W_net = ∆E_k

Potential Energy

A form of energy an object possesses because of its position in relation to forces in its environment

• Can be considered a stored form of energy.

Gravitational Potential Energy

Energy possessed by an object due to its position relative to the surface of the Earth

• E_g = mgh

Law of Conservation of Energy

Energy can neither be lost nor created

Mechanical Energy

The sum of the E_k + E_g

• E_m = E_k + E_g

10 Types of Energy

1. Mechanical

2. Gravitational

3. Radiant

4. Electrical Static

5. Electrical Current

6. Thermal

7. Sound

8. Nuclear

9. Elastic

10. Chemical

Energy Transformation

Changing one type of energy into another

• Ex: Electrical currents into radiant energy (lightbulb)

Describe the Energy Transformation of a diver in 3 different phases: (Height = 10m Mass = 65kg)

Phase 1: At the top of the diving board

Phase 2: In the middle of the dive

Phase 3: Making contact with the water

Phase 1: Kinetic energy is 0, and the GPE is 6.4 kJ

Phase 2: Kinetic energy and GPE are both an even split

Phase 3: Kinetic energy is 6.4 kJ and GPE is 0

Efficiency

Ratio between the amount of useful energy produced to the energy used

Sources of Energy

Energy Resources: Energy-rich substances

• Non-Renewable

• Renewable

Non-Renewable Energy Resources

1. Fossil Fuels

2. Nuclear Energy

Renewable Energy Reesources

1. Solar Energy

2. Hydroelectriciy

3. Geothermal

4. Wind

5. Tidal

6. Biofuels

Power

The rate at which work is done

SI Units: Watts

• 1 Watt = 1 J/sec

Electrical Power

The quicker electrical devices transform electricity, the stronger the energy.

Kinetic Molecular Theory

An increase in motion of particles in a substance increases warmth

A decrease in motion of particles in a substance decreases warmth

Thermal Energy

Total quantity of kinetic and potential energy possessed by the atoms and molecules of a substance.

• Absorption = More Heat

• Release = Less Heat

*NOTE - Thermal energy can be transferred only from a warmer object to a cooler one

Temperature

A measure of the average kinetic energy of particles in a substance

How does a thermometer work?

A thermometer tracks the temperature based on how much the particles are bouncing around. The hotter they are, the faster they move around, and vice versa.

Temperature Scale

The temperature scale based on the boiling point and freezing point of water

Fahrenheit Scale

Temperature scale based on the boiling point and freezing point of SALTWATER

Kelvin Scale

Temperature scale using absolute zero as the point at which there is no motion in particles of a substance.

Solar Energy

Radiant energy from the sun

Passive Solar Design

Building design that uses the Sun’s radiant energy directly for heating

Photovoltaic Cell

A device that transforms radiant energy into electricity

• When solar energy interacts with solids such as silicon, it transforms it into electricity.

Fossil Fuels

Fuel produced by the decayed and compressed remains of plants and animal from millions of years ago

• Ex: Natural gas, coal, gasoline, and diesel fuels

Nuclear Energy

A form of potential energy produced by the interaction in the nuclei of atoms.

• Produced by nuclear fission and nuclear fusion

4 Types of Renewable Energy

Geothermal: Transforms the thermal energy from the Earth’s core into electricity

Wind: Uses wind to spin a blade which turns an electricity generator.

Tidal: Uses the tide levels to spin an electricity generator.

Biofuels: Uses the gaseous fuels (chemical energy) from dead or alive organisms.