Energy Basics
Potential energy is the energy stored in an object because of its ______ or condition.
Position / height
Heat transfer through direct contact is called ______.
Conduction
At which point does a roller coaster have the greatest gravitational potential energy?
At the highest point
Energy efficiency is the percentage of ______ energy out compared to energy input.
Useful
Write the formula for kinetic energy.
EK=0.5×m×v2
Which form of energy is found in food?
Chemical
A vacuum in a Yeti Bottle prevents:
a) Conduction only
b) Conduction and convection
c) Convection only
d) Radiation only
b
At the bottom of a hill, the roller coaster has the greatest ______ energy.
Kinetic
If a lamp uses 300J and outputs 200J of light, what happened to the other 100J?
Transformed into heat
Write the formula for gravitational potential energy.
EP=m×g×h
Which is NOT a form of energy?
a) Mechanical
b) Chemical
c) Friction
d) Thermal
C
Name one good insulator and one good conductor.
e.g. Wool (insulator), Copper (conductor)
List atleast 5 types of energy that may be present in a roller coaster system.
Gravitational potential energy
Kinetic energy
Sound energy
Heat (thermal) energy
Chemical energy (in fuel, if powered)
Electrical energy (if motors are used)
Write the formula for energy efficiency.
Efficiency=Energy input/Useful energy output×100%
Calculate the potential energy of a 0.4 kg balloon dropped from 3 m.
11.76 J
What is the difference between energy transfer and energy transformation? Give an example of each.
Energy transfer: Energy moves from one object to another (e.g., heat moving from a stove to a pot).
Energy transformation: Energy changes form (e.g., chemical energy in food transforming into kinetic energy when you run).
Heat transfer from the Sun to Earth occurs by ______.
Radiation
Energy cannot be ______ or ______, only transformed.
Created or destroyed
A machine uses 500J of energy and outputs 350J of useful work. Calculate its efficiency.
70%
Calculate the kinetic energy of a 0.4 kg balloon thrown at 8 m/s.
12.8 J
A ball is dropped from 10 m. Which statement is TRUE about energy transformations:
1. Potential energy decreases, kinetic energy increases
2. Potential energy increases, kinetic energy decreases
1
Compare conduction and radiation (one similarity, one difference).
Both transfer heat; conduction needs particles, radiation does not
Why does a roller coaster never reach the exact same height on the next hill?
Some energy is lost as heat and sound due to friction
Why is energy efficiency important?
Reduces wasted energy and saves resources
If a mower has 2280J input and 1900J useful output, calculate efficiency.
83.3%