PhySci Final Review 2: Mechanical Energy

PhySci Final Review 2: Energy

By William Lovering

Energy

is the ability to do work or cause change.

EVERYTHING has energy, but different kinds.

All energy can be split into TWO categories:

Kinetic (movement) and potential (stored).

Energy

• "is the capacity to do work"

• measured in Joules (J) (pronounced like jewels)

• comes in many different forms/types

• CANNOT be negative

Subtypes of kinetic (movement) energy:

• Mechanical

• Radiant (light)

• Thermal

• Sound

• Electrical

Mechanical

movement/ motion of objects.

Radiant

any electromagnetic (EM) radiation.

Radio Waves

Microwaves

Infrared

VISIBLE LIGHT

Ultraviolet

X-Rays

Gamma Rays

Thermal

heat energy from the vibration/ movement of a substance's molecules.

Sound

movement of sound waves.

Electrical

movement of electrons.

Subtypes of potential (stored) energy:

• Gravitational Potential Energy (GPE)

• Chemical

• Nuclear

Gravitational Potential Energy (GPE)

energy of position or place, has the "potential" to move.

Chemical

energy stored in the bonds between atoms and molecules.

EX: FOOD, batteries, coal, gasoline

Nuclear

energy stored in the *NUCLEUS* of an atom.

NUCLEAR power plants, stars or atomic bombs ONLY!!!

Kinetic Energy

Potential Energy

GRAVITATIONAL potential energy

** if a problem does not give you g, g = 9.8 m/s²

Multiple Choice

What is stored energy due to position above the ground?

• kinetic energy

• potential energy

• thermal energy

• nuclear energy

Multiple Choice

What is energy due to motion?

• kinetic energy

• potential energy

• thermal energy

• nuclear energy

Multiple Choice

What is the sum of kinetic energy and potential energy of a system?

• mechanical energy

• electrical energy

• moving energy

• nuclear energy

Multiple Choice

Where does the pendulum have the greatest kinetic energy?

• A

• B

• C

• D

• E

Multiple Choice

Where does the pendulum have the least amount of potential energy?

• A

• B

• C

• D

• E

Multiple Select

Where does the pendulum have the greatest potential energy? (pick 2)

• A

• B

• C

• D

• E

Multiple Choice

Where is potential energy at its maximum?

• a

• b

• c

• d

Multiple Choice

What is the mechanical energy of the system? (ignore friction)

• 0J

• 10,000J

• 20,000J

• can not be determined

Multiple Choice

The sun provides ____________ and ____________ energy that can be harnessed and used for solar power.

• chemical, sound

• mechanical, light

• sound, light

• light, thermal

Multiple Choice

Energy can't be .....

• transformed.

• made or destroyed.

• converted.

• harnessed or produced.

Multiple Choice

Light is a form of __________ energy. 

• Sound 
• Electromagnetic
• Fun
• Thermal 

Multiple Choice

___________ energy can move through empty space.  

• Sound 
• Nuclear 
• Electromagnetic 
• Chemical 

Multiple Choice

This is the energy that moves objects. 

• cool 
• nuclear 
• chemical 
• mechanical 

Multiple Choice

This is the energy of vibrating molecules that move through matter. 

• sound 
• thermal 
• mechanical 
• electrical 

Multiple Choice

At the top of a hill, a car is sitting still and has 2,500 J of PE. What is the mechanical energy of the system?

• 2,500 J
• there is not enough information to answer the qustion
• 0 J

Multiple Choice

What is the correct unit for energy?

• meters (m)

• kilogram meters per second (kg m/s)

• Newtons (N)

• Joules (J)

Multiple Choice

The faster an object moves, the ________ kinetic energy it has. 

• more
• less
• none of the above
• all of the above 

Multiple Choice

Gravitational potential energy depends on the ________ and ________ of the object. 

• Height and mass
• Friction and movement
• Mass and Movement
• Height and Friction 

Multiple Choice

Calculate the potential energy of a car with a mass of 2,500 kg that is on a hill 100 meters above sea level. (g = 10 Nkg^-1)

• 250,000 J

• 2,500,000 J

• 25,000,000 J

• 250 J

Multiple Choice

Lilly's cat ran through your yard. The cat has a mass of 5 kg. He is running at a speed of 3 m/s. What is the kinetic energy of the cat as he runs? (KE = 1/2mv²)

• 8.5 J

• 45 J

• 7.5 J

• 22.5 J

Multiple Choice

If the 0.3 kg marble was moving at 6 m/s at the bottom of the ramp, how much kinetic energy did the marble have? (KE = 1/2mv²)

• 5.4 J

• 1.8 J

• 3 J

• 6 J

Multiple Choice

A exercise ball is on a table 2.5 m above the ground. What is the mass of the ball if it has a GPE of 56.8 J?

• 71 kg

• 22.72 kg

• 142 kg

• 2.32 kg

Multiple Choice

What is effort (input) force?

• the force one exerts on a machine

• the force which an effort force must overcome in order to do work on an object via a simple machine.

• the force the machine exerts on a object

• the output work times the input distance

Multiple Choice

How much work is produced when 350 N is used to move a car 5 m (W=Fd)?

• 70 J
• 1750 J
• 355 J
• 175 J

Multiple Choice

Is this an example of work?
A teacher applies a force to a wall and becomes exhausted.

• True
• False

Multiple Choice

if a load of a lever is 100 newtons and the force you apply is 20 newtons, what is your mechanical advantage?

• 120 N
• 5 N
• 2000 N
• 80 N

Multiple Choice

The amount by which a machine multiplies input force is known as the 

• work.
• power.
• output force.
• mechanical advantage.

Multiple Choice

the rate at which work is done

• power

• work

• machine

• efficiency

Multiple Choice

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 minutes?

• 15 J
• 45 J
• 0 J
• 5 J

Multiple Choice

45,000 Joules of work done in 90 seconds results in how much power?

• 50 watts
• 500 watts
• 5000 watts
• 4,050,000 watts

Multiple Choice

The efficiency of a machine can be increased by reducing __________________________. 

• effort
• resistance friction
• fulcrum
• friction

Multiple Choice

All simple machines help make work _________.

• harder
• smaller
• lighter
• easier

Multiple Choice

the force the machine exerts on an object

• input force

• output force

• efficiency

• mechanical advantage

Multiple Choice

a simple machine that is a flat, sloped surface

• inclined plane

• wedge

• lever

• fulcrum

Multiple Choice

a rigid bar that is free to pivot, or rotate, on a fixed point

• wedge

• inclined plane

• lever

• fulcrum

Multiple Choice

a simple machine made of a grooved wheel with a rope or cable wrapped around it

• pulley

• wheel and axle

• screw

• lever

Multiple Choice

3. Which type of lever is this?

• First Class Lever
• Second Class Lever
• Third Class Lever

Multiple Choice

6. What kind of lever is this?

• First Class Lever
• Second Class Lever
• Third Class Lever