Potential Energy
Is Potential Energy stored or moving?
Stored
What is the formula for percentage efficiency?
%Efficiency=Useful output/total input x 100
What are the types of kinetic energy
Thermal, Sound, Light, Electrical, Mechanical.
What is energy measured in?
Joules
What is the name of the diagram that is used to represent energy efficiency?
Sankey diagram
What are the 4 types of Potential Energy?
Gravitational, Elastic, Nuclear, Chemical
True or false. mgh is the formula for kinetic energy.
False
What is the formula for Kinetic energy?
1/2mv2
How do we know if energy is present?
All objects possess some form of energy.
Movement, heat, sound, presence of gravity, position/ height.
What is the formula for energy efficiency?
out/in x 100
What is the formula to calculate potential energy?
Mass x Gravity x Height
If Denise is holding a sack of potatoes that weighs 37.8Kg and is 1.2m above the ground how much gravitational potential energy does the sack of potatoes have?
441000J
A ball is thrown off of a cliff, right before it lands what kind of energy kinetic does it have.
Mechanical/ Kinetic and Thermal.
What is the law of conservation of energy?
Energy can neither be created nor destroyed it only changes forms.
Draw a Sankey diagram of a TV with 10,000 joules of electrical energy going in with 7000 joules of light energy, 2000 J of sound energy and 1000 joules of Heat energy.
On board
A 5kg rock is lifted to a height of 4m in 3s. Which of the following is false?
A. It's potential energy at the top is 200J
B. It's kinetic energy at the ground is 7.5J
B
Bobby is running at a speed of 0.5m/s on Mars (where the gravity is 3.71m/s2). Calculate the kinetic energy.
1/2 mass velocity squared.
A truck is driving along a highway at night. What types of Kinetic energy does it have?
Thermal, mechanical, sound, light, electrical.
What is the definition of energy?
Scientists define energy as the ability to do work.
If 2550 Joules of electrical energy is input into a toothbrush, 1672 Joules of energy is turned in kinetic energy and 250J is turned into heat energy and 628 of sound energy, draw a Sankey diagram of the toothbrush and find the energy efficiency of the toothbrush.
On board
How high must a 20kg box be lifted off the ground to give it 784J of GPE
3.92m
Timmy is holding a book that weighs 3000g and is 0.7m above the ground. Calculate the gravitational potential energy of Timmy.
20.58J for the book
BUT - the question actually asks about Timmy and he is on the ground!!
Draw an example for each type of Kinetic energy.
On board draw -
Is having no energy possible?
Absolute zero is where the kinetic energy of the particles is zero. That means all the motion between particles will cease. At Absolute Zero temperature (−273.15°C), all the molecules are expected to have no kinetic energy and hence no molecular motion.
I f lightbulb A produces 31J of light energy, 2J of sound energy and 7J of heat energy and Lightbulb B produces 105 J of light energy, 4 joules of sound energy and 12 J of heat energy, calculate which lightbulb has the higher energy efficiency.
Answer on board.