Proficiency ReviewJanuary 2015

Identify what each line indicates in the graph below:A to B - constant speed B to C - stopped C to D - increase speed D to E - stopped E to F - constant speed (returning to reference point)

Identify the average speed at position B.

2m/s

Formulas

Speed Avg SpeedVelocity

What are two ways you can increase the speed of an object?

• You can decrease the time it takes to travel a specific distance.

• You can increase the distance you have to travel in the same amount of time

Define Law Example/Explanation Key Terms to include

1st Law

2nd Law

3rd Law

An object at rest tends to stay at rest and an object in motion tends to stay in motion (due to inertia) unless acted upon by an unbalanced force.

The acceleration of an object is equal to the net

force exerted on the object divided by the

object’s mass.

Every action has an equal, but opposite reaction.

Inertia, unbalanced force

Force, mass, acceleration

Action/reaction

pairs

• What factor affects inertia?

• What two factors can increase gravitational attraction?

mass

Increase mass or decrease distance

Identify three types of friction and define each.STATIC –

SLIDING –

FLUID -

Friction that acts on objects that are not moving.

When solid objects slide over each other.

A force produced by a fluid (gases or liquids) Examples: engine oil, grease

Formulas

MomentumForce

𝑷=𝒎𝒗 F

Energy Definition Example

Kinetic The energy an object has because it is in motion.

Walking, moving car

Potential Stored energy that depends on the interaction of objects, particles, or atoms.

A kite in a tree

Chemical Energy that is stored in and released from the bonds between atoms.

A battery; cheeseburger

Radiant The energy carried by electromagnetic waves.

Visible light, electromagnetic spectrum

Thermal The sum of the kinetic energy and potential energy of the particles that make up an object

Heat

Energy Definition Example

Mechanical The sum of potential energy and kinetic energy in a system of objects.

Windmill, rollercoaster, turbine

Sound The form of energy associated with the vibration or disturbance of matter

Animals use echolocation

Nuclear Energy stored in and released from the nucleus of an atom

Sun – nuclear fusionUranium atom (in nuclear power plant) – nuclear fission.

Electrical The energy that an electric current carries is a form of kinetic energy.

Outlets, appliances

Gravitational potential

The stored energy due to height.

Kite stuck in a tree

Explain the difference between an energy transfer and an energy transformation.

Energy Transfer -

Energy Transformation –

the passing of energy from one object to another object

the changing of energy from one form of energy to another form of energy.

Is energy always conserved? Explain if you were dropping a tennis ball out of the

window.• Yes, energy is always conserved. Energy cannot be

created or destroyed, only transferred or transformed.

• When you hold the ball out of the window you have stored, potential energy. As you release the ball kinetic energy increases and potential energy decreases. When it hits the ground energy is transformed into sound, thermal and elastic potential energy as well. The total amount of energy is still present in different forms.

What is the relationship between kinetic and potential energy?

• PE and KE are inversely related.

• Example: At the top of a roller coaster you have large amounts of PE, but very little KE. As the roller coaster starts to move down the hill KE increases and PE decreases until it reaches the bottom with the greatest KE and least PE.

*The areas with most potential energy will transform into areas with greatest kinetic energy.

Identify an example of a multiple energy transformation. Identify what energies are involved with each transformation.

• Turning on a flashlight– Flipping the switch – mechanical energy– Battery – chemical energy– Wire – electrical energy– Light – radiant energy– Heat – thermal energy

Formulas

Mechanical EnergyPotential Energy

Kinetic EnergyEfficiency

22/1 speedmassKE

PE mass gravity height

x 100

orPE = weight x height

What is the kinetic energy of a jogger with a mass of 65.0 kg traveling at a speed of 2.5 m/s?

JoulesKEkgKE

speedmassKE

2035.2655.0

5.02

2

Find the gravitational potential energy of a light that weighs 1274 N and is 4.8 m above the ground.

PE = 1274N x 4.8m

6,115.2 Joules

As the a roller coaster is moving down the first hill it contains 12,000 J of potential energy and 3,000 J of

kinetic energy. How much mechanical energy is involved?

15,000 Joules

Which color has the highest frequency on the electromagnetic spectrum?Which color has the lowest frequency on the electromagnetic spectrum??

violet

red

Which are each of the following scientists known for?

• Sir Isaac Newton –

• Albert Einstein –

• Johannes Kepler –

• James Prescott Joule -

Newton’s Laws of Motion and the Universal Law of Gravitation

Identifying that small amounts of matter can promote large amounts of energy E=mc2

Planetary Laws of Motion

His findings allowed scientists to establish the law of conservation of energy.

What can you do to increase the Kinetic Energy of an object? Increase Mass or Increase Velocity What kind of relationship is that?

Increase Mass, Increase Kinetic EnergyIncrease Velocity, Increase Kinetic Energy Direct

What is the greatest Kinetic Energy of the object above? 90 J

A 4 kg kitten was running at a velocity of 6 m/s. Calculate the KE of the kitten and explain if it had more/less kinetic energy that the object above.

KE=1/2*m*v2

KE=1/2*4*62

KE=72 J

Kitten had less KE!