Forms of Energy
What is the basic unit of energy in the International System of Units (SI)?
Joules (J)
What is an example of kinetic energy?
An object moving.
Define potential energy and provide an example of an object with high potential energy.
stored energy. when an object is at its highest point.
Provide an example of a common energy transformation in everyday life.
toaster oven. electrical to heat
Provide examples of renewable energy sources.
solar energy, wind, falling water, the heat of the earth (geothermal), plant materials (biomass), waves, ocean currents, temperature differences in the oceans and the energy of the tides.
Give an example of potential energy and explain how it can be converted into kinetic energy.
Gasoline
Gasoline to a Car
How does the kinetic energy of an object change when its mass doubles but its velocity remains constant?
Kinetic Energy increases.
How does the height of an object affect its potential energy?
The heavier the object and the higher it is above the ground, the more gravitational potential energy it holds.
Explain how a toaster transforms electrical energy into thermal energy.
The electrical energy flows through metal conductors in the toaster that have high resistance to current flow. This causes the metal to heat up to the point where they glow.
Explain the relationship between power and energy.
Power is how fast energy is used or transmitted - power is the amount of energy divided by the time it took to use the energy.
How is thermal energy transferred between objects?
Through conduction, convection, and radiation
Give an example of an everyday object with high kinetic energy and explain why.
An asteroid falling towards Earth exhibits a tremendous amount of kinetic energy due to its large mass and high velocity. During flight, an airplane has a higher kinetic energy due to its substantial mass and fast velocity.
Explain elastic potential energy and give an example.
The energy than an object has in it due to being deformation of its shape. Any object which can be deformed and then return to its original shape, then it can have elastic potential energy. Examples of such objects are rubber bands, sponges, and bungee cords, and many others.
Describe the energy transformations in a car engine.
The internal combustion engine in the car converts the potential chemical energy in gasoline and oxygen into thermal energy which is transformed into the mechanical energy that accelerates the vehicle (increasing its kinetic energy) by causing the pressure and performing the work on the pistons
Explain how solar panels convert sunlight into electricity.
When the sun shines onto a solar panel, energy from the sunlight is absorbed by the PV cells in the panel. This energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flow.
Explain the law of conservation of energy.
Energy cannot be created or destroyed. It can only change forms.
How does air resistance affect the kinetic energy of a falling object?
Kinetic energy dissipates into local gas particles and is also converted to thermal energy by friction on the surface of the projectile.
Describe how gravitational potential energy is related to an object's mass and height.
The heavier the object and the higher it is above the ground, the more gravitational potential energy it holds. Gravitational potential energy increases as weight and height increases.
How is chemical potential energy transformed into thermal energy during combustion?
During combustion, chemical bonds are broken and reformed (changing gasoline into byproducts such as water and carbon dioxide), releasing energy.
How does friction affect the energy of a moving object?
The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down. When objects move through a fluid, such as air or water, the fluid exerts a frictional force on the moving object. The frictional force from a fluid is called a drag force.
Describe the energy transformation involved when a person riding a bike comes to a stop.
Kinetic energy to heat energy.
Discuss the factors that influence the kinetic energy of a moving car.
The kinetic energy stored in a moving vehicle is related to the mass and speed of the vehicle - if your car is twice as heavy it has twice the kinetic energy and if it is moving twice as fast it has four times the kinetic energy.
Discuss the potential energy changes involved when a stretched rubber band is released.
By remaining in a stretched condition, the rubber is in a state of high potential energy, when the force holding the rubber in place is removed, due to the laws of thermodynamics, the polymers in the rubber curls back to their state of "random" tangled mass releasing the stored potential energy
Discuss the various energy transformations involved in a hydroelectric power plant.
When the water flows from higher altitude, the potential energy is converted into kinetic energy. When the flowing water rotates the turbine, the kinetic energy is converted into mechanical energy. The generator converts mechanical energy into electrical energy.
Discuss the advantages and disadvantages of nuclear energy.
Nuclear plants cost billions of dollars to build and they take much longer than any other infrastructure for renewable energy, sometimes even more than a decade. However, while nuclear power plants are expensive to build, they are relatively cheap to run, a factor that improves its competitiveness.