Energy in Everyday Life
A toaster is plugged in and heats up bread. Name the energy transformation.
Electrical energy transforms into thermal energy.
A skateboarder rolls from the top edge of a half-pipe to the bottom. What happens to her kinetic energy?
It increases.
True or False: Energy can be created if you have the right machine.
False — machines only convert energy from one form to another.
A pendulum has 60 J of potential energy and 0 J of kinetic energy at the top. With no friction, what is its kinetic energy at the bottom?
60J
What type of energy does a stretched bow have?
Elastic Potential Energy
A solar panel is used to charge a phone. Name the energy transformation.
Light energy transforms into electrical energy.
A trampoline jumper pushes down into the mat. What does their kinetic energy become?
Elastic potential energy stored in the mat.
True or False: A ball that stops bouncing has had its energy destroyed.
False — its energy was transformed into thermal and sound energy.
An object has 25 J of kinetic energy and 75 J of potential energy. What is its total mechanical energy?
100 J
What type of energy does a marble sitting on a high shelf have?
Gravitational potential energy.
A wind turbine's blades spin to generate electricity. Name the energy transformation.
Kinetic energy transforms into electrical energy.
A bow is pulled back and an arrow is released. Name the energy transformation.
Elastic potential energy transforms into kinetic energy.
True or False: The law of conservation of energy applies no matter how much an object's mass is.
True
A roller coaster car has 400 J of total mechanical energy. At the bottom of a hill, it has 400 J of kinetic energy. What is its potential energy there?
0 J
What type of energy is stored in a candy bar before you eat it?
Chemical potential energy.
Water falls over a dam and spins turbines to make electricity. Name the two-step energy transformation.
Gravitational potential energy transforms into kinetic energy, then into electrical energy.
A car's brakes bring it to a stop. Where does its kinetic energy go?
It transforms into thermal energy (heat) in the brakes.
True or False: In a closed system, total energy can increase over time.
False — total energy in a closed system stays constant.
A pendulum's total mechanical energy is 120 J. At one point it has 45 J of kinetic energy. What is its potential energy at that point?
75 J
What type of energy does a spinning bicycle wheel have?
Kinetic energy.
A guitar string is plucked and makes a sound. Name the energy transformation.
Kinetic (mechanical) energy transforms into sound energy.
A cyclist has to keep pedaling on flat ground just to maintain speed. Name the two forces converting her mechanical energy into heat.
Friction and air resistance.
True or False: Friction transforms energy into heat and sound rather than destroying it.
True
A ball is released with 90 J of potential energy. Halfway down, with no friction, it has 40 J of kinetic energy. How much potential energy does it have at that point?
50 J
What type of energy is produced when two sticks are rubbed together until they feel warm?
Thermal Energy