Quarter 1 Grade Recovery

Motion, Speed, and Velocity

SCI8_Stewart​

What is motion?

Motion is when an object changes place or position.

To properly describe motion, you need to use the following:

• start and end position?

• movement-relative to what?​

• how far did it go?

• in what direction did it go?​

How can we measure motion?

​Distance: How far an object is from one position to another.

• Can be measured

• units of distance: cm, meter, inches, kilometers, miles​, etc.

​Time: How long it takes an object to travel from one position to another.

• Can be measured

• units of time: seconds, minutes, hours, days, years. etc/​

​Speed: The distance an object moves in a certain amount of time.

• Can be measured

• units of distance: mph (miles per hours), etc.

• Formula to calculate speed: distance divided by time + speed​

What is Speed?

​Speed: The distance an object travels divided by the amount of time it takes to travel that distance. s=d/t

• a car may go 60 mph (miles per hour)

• The train can travel 100 miles in 2 hours

• ​What is the speed of the train?

• Answer in Open Chat.​

What is Velocity?

​Velocity: The speed an object is traveling in a specific direction.

• For example, a car driving east at 60 mph would have a velocity of 50 mph east

• Velocity ALWAYS includes direction of motion (north, south, east, west, + or - (if along a strait line), up, down, etc.

• Speed DOES NOT include direction

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Multiple Select

What does speed measure?

• the distance covered in an amount of time

• distance divided by time

• both a and b

• neither answer is correct

Multiple Choice

What is the velocity of a car heading 200 miles west in a time of 5 hours?

• 40 mph West

• .4 miles/hour West

• 40 mph

• .4 mph

Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity.

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• An object is accelerating if it is changing its velocity.​

• So, it will look like meters/second/second or m/s/s

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Acceleration

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Acceleration could mean speeding up...that is the obvious one of course.​

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Examples of Acceleration

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Acceleration could also mean to slow down!

• ​Yes...acceleration actually means ANY change in speed--even if that means slowing down!​

• Positive acceleration would be an increase in ​speed

• Negative acceleration would be a decrease in speed​

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Acceleration not only means a change in speed (either increasing OR decreasing), it also means a change in DIRECTION!!!

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Yes, when you go around a curve or turn one way or another, even if you do it slowly, you are ​considered to be ACCELARATING!!!

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Acceleration is weird...

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Multiple Choice

If a car is increasing its speed from 10 mph to 50 mph; what is the car doing?

• accelerating

• speeding

• stopping

Multiple Select

If a car is decreasing its speed from 50 mph to 20 mph; what is the car doing?

• accelerating

• accelerating

• accelerating

• YES, the correct answer is ACCELERATING! PICK THIS ONE!!

Multiple Choice

If a car comes around a curve in the road and proceeds to safely follow the curve and keep on going, what did the car do in the curve even though it never changed its speed?

• The car accelerated by changing direction and keeping the speed the same.

• The car simply turned...it has nothing to do with acceleration.

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Multiple Select

According to the video, what are the units for acceleration?

• M / s²

• Meters per second squared

• meters per second per second

Multiple Select

If a car goes from 0 meters/second to 60 meters/second in 30 seconds, what is its acceleration?

• 2 M/s²

• .2 M/s²

• 2 meters per second per second

• .2 meters per second per second

Multiple Choice

If a car goes from 10 meters/second to 40 meters/second in 6 seconds, what is its acceleration? (remember to subtract the initial speed from the final speed to get your actual speed)

• 5 M/s²

• .5 M/s²

• 50 meters per second per second

• .05 meters per second per second

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Multiple Choice

What does initial velocity mean?

• Initial velocity is the starting value of an objects velocity before something happens to change it

• Initial velocity is the speed when something changes

• initial means the letters of my name

• initial is the last velocity something has

Multiple Choice

A bicyclist is traveling at a velocity of 15 meters per second and crashes into a brick wall, reducing their velocity to 0 meters per second in 0.5 seconds. What was their negative acceleration in this instance?

• -30 meters / second squared

• 30 meters/second squared

• 15 meters/second squared

• -15 meters/second squared

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Multiple Choice

If an object is speeding up, what is the value of the acceleration?

• positive acceleration

• negative acceleration

Multiple Choice

If an object is slowing down, what is the value of the acceleration?

• positive acceleration

• negative acceleration

• speeding up is considered a positive acceleration

• slowing down is considered a negative acceleration

• changing direction could be either a negative or positive acceleration depending on the change that takes place

​Acceleration Review

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• Δ  is a symbol that means a change in something...so when you see that symbol of the triangle you know you will be subtracting the initial velocity from the final velocity

• a is the letter that means acceleration

• t is the letter that means time

​Calculating Acceleration

Multiple Choice

Δv= 45 m​ /s 

 t=5s  

What is the acceleration of this system?

• 9 m/s²

• 0.9 m/s²

•  5 m/s²​  

You are awesome!

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yes, you are....

​Great job!

Net Force

Multiple Choice

Balanced forces acting on an object will

• change the motion of that object

• not change the motion of that object

• do nothing

• make the object stop

Multiple Choice

Unbalanced forces acting on an object will

• change the motion of that object

• not change the motion of that object

• do nothing

• make the object stop

Friction

Multiple Choice

From that video, what two forces were interacting between the block of wood and the ramp?

• Friction and Gravity

• Balanced and Unbalaced

• Normal and Un-normal

• No forces

Multiple Choice

To find the net force when the forces are working in the same direction you will

• add the forces together

• subtract the forces from each other

• divide the forces

• multiply the forces

Multiple Choice

To find the net force when the forces are working in opposite directions you will

• add the forces together

• subtract the forces from each other

• divide the forces

• multiply the forces

Multiple Choice

What is the net force in this scenario?

• 5 Newtons Right

• 10 Newtons Right

• 15 Newtons Left

• 20 Newtons Left

Multiple Choice

What is the net force in this scenerio?

• 5 Newtons Right

• 10 Newtons

• 0 Newtons

• 15 Newtons Left

Multiple Choice

What is the net force in this scenario?

• 10 Newtons right

• 10 Newtons Left

• 15 Newtons Left

• 25 Newtons Right

Static Electricity

Building Electric Charges

How Does It Happen?

• Electric Charges Build Up (Friction causes electrons to build up on an object)

• Then JUMP (ZAP)!

• The JUMP is called Static Discharge

Multiple Choice

When friction between two objects causes electrons to build up on one object it is called

• electric charge

• electric force

• electric drive

• gravity

Multiple Choice

When electrons suddenly jump from the object they have built up on that is called static discharge.

• True

• False

Where Does It Happen?

• Anywhere electric charge build up.

• Natural electricity

Multiple Choice

Static electricity is the _______________ form of electricity.

• human-harnessed (man-made)

• natural

Multiple Choice

Where does static electricity happen?

• where there are electrical wires

• anywhere electric charges build up

• only in outer space

• underground

Example of Static Electricity

• Lightning

• Negative Particles in Clouds JUMP to Positive Areas - Opposites Attract

• Static Discharge

Multiple Choice

Lightning can only travel from the sky to the ground.

• True

• False

Multiple Choice

Lightning happens when there is

• static discharge

• static distancing

• electric fencing

• not enough electric charge

Example of Static Electricity

Shocks

Build Up of Electrons on You Suddenly JUMP to a Metal

Static Discharge

Multiple Choice

On dry, winter days, you feel a shock when

• extra neutrons jump off your body onto a metal object

• extra electrons jump off your body onto a metal object

• extra protons jump off your body onto a metal object

Multiple Select

Click all that are examples of getting an electric shock from static electricity.

• person shocking another person by touching them

• person getting shocked by touching metal frame as they are getting off a trampoline

• person getting shocked by grabbing an electric fence

• person getting shocked by holding a live electrical wire

Example of Static Electricity

Static Cling

One object has a negative electric charge (gained electrons), one object has a positive electric charge (lost electrons) - Opposites Attract

Multiple Choice

Electric force causes electrically charged objects with opposite charges to

• attract

• repel

Multiple Choice

All examples of static cling happen in a clothes dryer.

• True

• False

Example of Static Electricity

Hair Stands Up

All hairs have extra negative electrons and push apart from each other causing hair to stand (likes repel)

Multiple Choice

In order for static electricity to cause your hair to stand up, your hairs must all have the

• same charge

• different charges

• no charge at all

Multiple Select

Which of these activities could cause static electricity to make your hair stand up?

• jumping on trampoline

• sliding down a slide

• pulling a sweater over your head

• touching a Van de Graaff generator

Magnets and Electromagnets

Permanent Magnets

Definition: A magnet that retains its magnetism after being removed from an external magnetic field.

Not all metals are magnetic

• Iron

• Cobalt

• Nickel

• (Steel - an alloy of metals that contains Iron)

Magnetic Fields

Definition: A magnetic field is the region around a magnet where a force acts on another magnet or on a magnetic material.

The Earth's magnetic field

• The Earth behaves as if it contains a giant magnet. It produces a magnetic field in which the field lines are most concentrated at the poles.

• This magnetic field can be detected using magnetic materials or magnets.

  
  

4 Rules of field lines

• 1. Field lines never cross
• 1. field lines run North to South
• 1. field lines are continuous
• 1. The closer the field lines are to each other the stronger the magnetic field is. Field lines are strongest at each Pole (North and South)

Rules of magnetism

Like Poles repel each other ( North - North and South - South)

Unlike Poles attract each other (North - South)

A compass

• a magnetic needle mounted on a pivot (so it can turn freely)

• a dial to show the direction

The Compass

• The north pole (north-seeking pole) of the compass needle points towards the Earth’s north pole. If the needle points to the N on the dial, you know that the compass is pointing north. This lets you navigate outdoors using a map

Question?????

If the North Seeking Pole of the compass needle is attracted to NORTH, what does that mean about the north seeking compass needle?

Fill in the Blank

Name one magnetic metal

Open Ended

Can you explain what a magnetic field is?

Multiple Choice

What are the two poles on a magnetic?

• East and West

• North and South

• Red and Blue

Multiple Choice

In which direction to magnetic field lines run?

• South to North

• North to South

• East to West

• West to East

Multiple Choice

Like Poles.....

• attract

• repel

• do nothing

Multiple Choice

Unlike Poles.....

• attract

• repel

• do nothing

Fill in the Blank

what device can be used to plot the magnetic field lines around a magnet?

Multiple Choice

At which point around a magnet is the magnetic field the strongest?

• its the same everywhere

• North pole

• South pole

• North and South poles

Open Ended

If the North Seeking Pole of the compass needle is attracted to directional NORTH, what does that mean about the north seeking compass needle?

Electromagnets

Electromagnet definition: A device consisting of an iron or steel core that is magnetised by electric current in a coil that surrounds it. 

Electromagnets

• When an electric current flows in a wire, it creates a magnetic field around the wire.

• This effect can be used to make an electromagnet. A simple electromagnet comprises a length of wire turned into a coil and connected to a battery or power supply.

  
  

Electric bell. 1

• The switch is open and the metal arm is away from the gong.

Electric Bell. 2

The switch is closed. An electric current flows through the electromagnet, producing a magnetic field.

Electric Bell. 3

The metal arm is attracted to the electromagnet. It hits the gong which makes a sound. The circuit is broken and the electromagnet turns off.

Electric Bell. 4

The metal arm springs back. The contacts touch and the circuit is complete again.

Electromagnets have some advantages over permanent magnets.

• For example:

  they can be turned on and off the strength of the magnetic field can be varied

• These properties make electromagnets useful for picking up scrap iron and steel in scrapyards.

Open Ended

What is an electromagnet?

Open Ended

What 3 things can you do to increase the strength of an electromagnet?

Open Ended

Give two examples where electromagnets are used in every day life?

Multiple Choice

Why is an advantage of an electromagnet over a permanent magnet?

• used to control high voltages

• cheaper

• lighter

• can find them in more places