Vocabulary
the ability to do work
energy
When something is held high in the air, what type of energy does it have?
Potential energy
the biggest source of light energy for Earth
the sun
Work depends on what two things? (hint: think about the formula for work)
force acting on the object and distance the object moves
What does an increased amplitude indicate about a wave's energy?
the energy is also increased
Which type of energy is related to an object's motion?
mechanical energy (kinetic energy)
When a ball hits the ground, all of it's ........... energy has been converted into ......... energy
potential energy...... kinetic energy
this form of energy cooks food in boiling water
thermal/heat energy
Which unit is Power measured in?
Watts
These types of waves need a medium through which to travel (transmit their energy).
Name it and give an example.
Mechanical waves. Sound waves.
______ energy is the only source of energy we can see.
Light Energy
A pendulum swings. In a perfect system (no friction), it would continue to swing forever. Why? Name the scientific principle.
Law of Conservation of Energy
What form of energy is found in the nucleus of an atom?
nuclear energy
You are waiting in line for Taylor Swift's new album release holding your backpack up with a force of 5 N. The line hasn't moved for 30 minutes.
How much work did you do? Round to the nearest tenth.
0.0 J because you have not changed your distance (work = Force x distance)
Which wave from the visible light part of the EM spectrum has the highest frequency and energy?
violet
This is the unit for both energy and work
Joules or J
Calculate the amount of potential energy a soccer ball with a mass of 0.43 kg has if it is held 2.5 m from the ground. (round to the nearest tenth)
10.5 J
What energy CHANGE takes place when someone plugs a coffee maker into an electrical outlet? (name the transformations)
electrical energy transforms into thermal energy
A -- a bodybuilder bench pressing 445 N (about 100 lbs.) in 30 seconds
B -- a bodybuilder bench pressing 1112 N (about 250 lbs.) in 2 minutes
Assume the distance they are moving the bar is the same.
Fun Fact: the current world record is 782 lbs!
A -- 445 N / 0.5 min = 890 Watts
B -- 1112 N / 2 min = 556 Watts
What happens to the energy of a wave when it is absorbed by a material?
(increases, decreases, stays the same)
it decreases
What is the Law of Conservation of Energy?
Which has more kinetic energy?
a. a ball with a mass of 4 kg traveling at a speed of 1.0 m/s
b. a ball with a mass of 1 kg traveling at a speed of 4.0 m/s
KE = (0.5)(mass)(velocity)2
a = (0.5)(4 kg)(1 m/s)2 = 2.0 J
b = (0.5)(1 kg)(4 m/s)2 = 8.0 J, so ball B has more kinetic energy; it's lighter but it is traveling faster.
Which 4 energy transformations take place when coal is burned to generate electricity?
A person weighs 250 N. They walk up the stairs from the 1st floor to the 3rd floor, covering a distance of 15 m. They talk with their friends, so it takes them 1.5 minutes.
How much power was used? **hint -- two step problem**
Work = Force x distance
Work = 250 N x 15 m = 3750 J
Power = Work/Time
Power = 3750 J/1.5 min = 2500 Watts
Would a sound wave travel faster in: the air, the ocean, or the metal hull of a ship? Explain why -- draw an image or write a written explanation
the metal hull of a ship because it's a solid; solids are DENSER than liquids and gasses, therefore particles are closely packed together and the energy can travel through them faster