Forces & Interactions Vocal Flashcards
Definition of Mass
The amount of matter in an object.
(Each time you add an atom to an object, you add mass)
Definition of Weight
The force of gravity upon an object.
Mass and Weight mean ____________ things.
Different
Formula for finding Weight
Weight = ___________ x ____________
Weight = mass x gravity
What is this thing?
(scroll down and look at entire picture)
Your secret weapon to get 4 questions right on the upcoming test.
What can this tell you about mass and weight?
The Earth’s gravity applies a force of
9.8-Newtons to a 1-kg mass
If you took this thingy to the moon and looked at it, the mass would _______________?
Stay the same.
The 1-kg label on th object will still say 1-kg, and it will still be correct.
If you took this thingy to the moon and looked at it, the weight would _______________?
Go down.
The moon has less gravity, so the red needle would only point to about 2.
What can this thingy tell you about weight?
Weight is a force.
The force of gravity upon an object
weight
Two definitions of acceleration
Change in speed or direction
or
Change in Velociy
Formula for acceleration
Accleration =
Acceleration = change in velocity/change in time
can also be written as:
a = Δv / Δt
Mass means pretty much the same thing as ________
Inertia
Three most common types of interaction
Touch
Gravity
Friction
If there is no air friction, which would experience a greater acceleration when dropped off a cliff, a large rock or a small rock?
Neither, both would accelerate at the same rate, and both would reach the ground at the same time.
Gravitational Field Strength near the Earth’s surface
9.8 newtons/kilogram
Net Force
The overall force that remains after all “cancelling” of forces has been taken into account.
What are these things?
Ball Bearings
(You have these on your bicycle, on your skateboard, inline skates, cars, etc.)
(These are what allow wheels to roll with very little friction.)
The word “static” means….
at rest
Static Friction means
The force of friction preventing a motionless object from moving.
Sliding Fricition means…
The force of friction impeding the motion of an object sliding across a surface.
Air Friction
The force of friction impeding the motion of an object fighting its way through the air.
(It has to bump the air molecules out of the way)
You can reduce the friction between to sliding surfaces by coating the surfaces with a ______________.
Lubricant
(oil, grease. etc)
What would happen to your mass if you left Earth and went to Jupiter?
Nothing.
Mass is a measure of how much “stuff” or matter there is in an object.
What would happen to your weight if you left Earth and went to Jupiter?
Your weight would go up.
Jupiter has a much stronger gravitational field than the Earth. Weight is the pull of gravity upon an object.
Interaction
When two objecst have an effect upon each other.
What does this stand for?
ΣF
Sum of Forces
Sum of Forces, or ΣF, means the same thing as:
Net Force
Friction
The force impeding the motion of an object scraping across a surface or plowing through the air.
Kinetic Friction
The force impeding the motion of a moving object.
Unbalanced Force means that the Net force is ___________.
Non-Zero
Normal Force
A force at right angles to a surface
A force that is perpendicular to a surface
Normal Force
Equilibrium
When all forces upon an object cancel out.
If an object has a constant velocity, what other things do you know?
Net Force = Zero
Acceleration = Zero
Sum of Forces = Zero
Its in Mechanical Equilibrium
If an object has a Net Force = Zero, what other things do you know?
It has a constant velocity
Acceleration = Zero
Sum of Forces = Zero
Its in Mechanical Equilibrium
If an object has an acceleration of zero what other things do you know?
It has a constant velocity
Net Force = Zero
Sum of Forces = Zero
Its in Mechanical Equilibrium
If the Sum of Forces upon an object is zero, what other things do you know?
It has a constant velocity
Net Force = Zero
Acceleration = Zero
Its in Mechanical Equilibrium
Air resistance
The force, caused by the air, opposing the motion of an object.
If an object is in equilibrium, what other things do you know?
It has a constant velocity
Net Force = Zero
Acceleration = Zero
Sum of Forces = Zero
Uniform Acceleration
A constant, steady acceleration caused by a constant, steady net force.
(Hint, in high school science, all accelerations studied will be uniform.
An object is in free fall when….
the only force acting upon it is gravity.
(The object could be going up, sideways, or down)
An object has been thrown upward. The only force acting upon the object is gravity. We would say that this object is…
in free fall.
An object has been thrown sideways off of a cliff. The only force acting upon the object is gravity. We would say that this object is…
in free fall.
Inclined Plane
A hill.
(A plane is a flat surface. If it is inclined, you have a hill)
The purple part below.
Inclined Ramp
An angled surface you might push or pull an object up.
In the picture below, the box is being pulled up the green “Inclined Ramp.”
An object that is “falling freely” is
in free fall.
(Has only one force acting upon it…gravity)
Resistance
The act of opposing something.
Gravity
A force that exists between ANY two objects that have mass.
Earth’s Gravitational Field
The area around the Earth that is influenced by the Earth’s gravity.
(Put an object in Earth’s gravitational field and it will tend to “fall” toward the Earth)
Moon’s Gravitational Field
The area around the Moon that is influenced by the Moon’s gravity.
(Put an object in the Moon’s gravitational field and it will tend to “fall” toward the Moon)
Jupiters’s Gravitational Field
The area around Jupiter that is influenced by Jupiter’s gravity.
(Put an object in Jupiter’s gravitational field and it will tend to “fall” toward Jupiter)
“Weigh an Object”
Using a scale to find out how much gravity is pulling down upon an object.
(Note: the reading on the scale would change if you went to the moon.)
What is the strength of Earth’s gravitational Field
9.8 N/kg
This means that the Earth will apply a gravitational force of 9.8 newtons for every 1 kilogram of mass.
Reaction Time
The interval between a stimulus and your response.
Example:
The time between when you see a mouse and when you scream.
“At Rest”
Not moving
Suspended
Hanging From
“Acted Upon”
“To exert or have an effect upon.”
A force of 20 Newtons “acted upon” the the block to the right.
“follows a straight-line-path”
moves in a straight line
Inertia
An object’s resistance to a change in velocity.
(Means almost the same thing as mass)
Towed
Pulled
What is this?
Its a bottle rocket!
(Rockets like this are often used to illustrate Newton’s Third Law)
(Notice, the water shoots down, the rocket shoots up)
“Mass an Object”
Using a balance to determine the mass of an object.
(Note: if you took this to the moon, the balance would still read the same amount. Why?)
Constant Speed
Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!Ding!
Net Force = 0
Sum of Forces = 0
Its in Equilibrium
Newton’s First Law
Acceleration = 0
Blah blah blah blah blah bladdady blah constant speed blah blah blah blah blah blah yada blah.
Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!
Net Force = 0
Sum of Forces = 0
Its in Equilibrium
Newton’s First Law
Acceleration = 0
What is the ONLY reason some obects fall more quickly than others when released?
Air Friction!
If there were no air, ALL objects would fall at the same rate.
Yadda blah, yackity yack blahdidy blah, at a constant velocity blah yaddidy blah yabba dabba do diddtily bloogalsnort.
Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!Ding! Ding! Ding! Ding! Ding! Ding!
Net Force = 0
Sum of Forces = 0
Its in Equilibrium
Newton’s First Law
Acceleration = 0
Satellite
Any object that orbits the Earth
(Spaceships, the moon, asteroids, etc)
Non-Zero
Not equal to zero
“Applied”
Put upon.
“A 13-N force was applied to a rock,” means that you pushed or pulled on the rock with a force of 13-N.
Frictionless
No friction AT ALL.
Even more slippery than the slipperiest ice!
“Releases”
Drops
This would mean that you didn’t “throw” the object down, so it starts with an intitial velocity of zero.
“Released”
Dropped
(Again, initial velocity is zero)
“Drops”
Not thrown up or down.
(If a boy “drops” a rock off a cliff, the initial velocity would be zero)
“Throws”
Gives an initial velocity to.
(Can be up, down, or any other direction)
Variable
Changing
A “variable” horizontal force acted upon the object.
What does the word, “experience” mean in the following context?
The object “experienced” a lot of friction.
It means “encountered” or “was subjected to.”
The object “encountered” a lot of friction
The object “was subjected to” a lot of friction.
What does “neglecting” mean in the following sentence?
“Neglecting” air friction, the Earth’s gravitational field causes object to accelerate at 9.8 m/s2.
It means “Ignoring”
“neglecting air friction,” means the same thing as “ignoring air friction.”
What does the word “falls” mean in the following sentence?
A rock “falls” from the edge of a cliff.
V0 =0 m/s
“Falls” means that the rock was not thrown down or up. Thus, it has an intial velocity of zero.
What does the word “approximately” mean in the following sentence?
The weight is “approximately” 5-newtons
It means “close to” or “about.”
For example, if the weight is truly 4.9-newtons,
we could say it is “approximately” 5.0-newtons
or “about” 5.0-newtons.
What SI measurment unit would you use to measure weight?
Newtons
Weight is a force.
What are two things you could change about a car that would increase its ability to accelerate?
Make it lighter
Make the engine more powerful.
Less mass means more acceleration and more force means more acceleration.
True/False
The soccer ball shown in the picture is in “Free Fall.”
True.
It doesn’t matter if the ball is going up, down, or sideways. As long as the only force acting upon the ball is gravity, it is in “Free Fall.”
True/False
The entire time between when this cannonball
leaves the cannon until it hits the ground,
the cannonball is in
“Free Fall.”
True.
Once it leaves the cannon, the only force acting upon the cannonball is gravity.
True/False
This fighter jet is in “Free Fall.”
False.
This fighter jet has more forces acting upon it than just gravity. It is experiencing the following forces:
- Gravity
- “Lift” (from the air on the wings)
- “Thrust” (generated by the afterburners)
In which direction would the net force be upon this object?
To the left.
What would be the net force upon this object?
100 Newtons upward
What would the net force be upon this object?
2 N to the right
What would be the net force upon this object?
1 Newton to the right.
What would be the net force upon this object?
10 N to the left.
What would be the net force upon this object?
10 Newtons to the left.
What mathematical calculation would you do to determine the net force upon the skydiver shown here?
Net Force = (Force of Gravity) - (Force of Air Friction)
What would be the net force upon this object?
30 N to the right
What would be the net force upon this object?
30 N to the right.
“Free Fall”
When the ONLY force acting upon an object is gravity.
This can be after an object is dropped.
It can also be after an object is thrown up.
It can even be after an object is thrown sideways.
In all these situations, the only force acting upon the object is gravity.
Net Force
The overall force acting upon an object.
Touch
Gravity
Friction
The three things we often think about when we are looking for forces.
Gravity
A force between any two objects with mass
Air Friction
The force impeding the motion of an object traveling through the air.
Tension
A force exerted by a string or rope.
In physical science the word “Normal” means
Perpendicular.
Inertia
VERY close in meaning to “mass”
BUT
Inertia is usually used when you are talking about stopping a moving object or making a stationary object start moving.
Newton’s First Law
Objects in motion stay in motion
Objects at rest stay at rest
If its moving, it will keep moving in a straight line, at the same velocity, FOREVER, unless acted upon by a net force.
Newton’s Second Law
A = F/M
(Acceleration = Force divided by Mass)
The blue line could also be consider to be ______________ to the red surface
“Normal”
(In physics, “normal” and “perpendicular” mean the same thing)
All of the red lines are ____________ to the red curve.
“Normal”
(In physics, “normal” means “perpendicular to”)
More mass means more ___________.
Inertia
Any object experiencing zero net force will ALWAYS have _______________
Zero Acceleration
The size of the force of air friction is dependant upon
______________
and
_______________
The size and shape of an object
and
The speed at which the object is moving relative to the air.
Newton’s Third Law
For every action, there is an equal and opposite reaction.
In Newton’s Third Law, which happens first, the action or the reaction.
Neither!
The “action” and “reaction” forces always happen at the exact same time.
True or False
“An object in equilibrium cannot be moving.”
FALSE
(An object in equilibrium could be either stopped or moving with a constant velocity)
True or False
“An object in equilibrium must be moving.”
FALSE
(An object in equilibrium could be either stopped or moving with a constant velocity)
Force
Vector Quantity or not?
Vector
50 newtons downward has both magnitude (50) and direction (downward).
So, its a vector or vector quantity.
Newton’s Second Law
A = F/M
(Acceleration = Force divided by Mass)
Mass
How much “stuff” there is in an object.
(or how much matter)
(each added atom or molecule adds mass)
If an object is not accelerating, you can be absolutely positive that it is experiencing ________________.
Zero Net Force
True or False
This motorcycle rider is in “Free Fall.”
True.
Once he goes off the jump, the only force acting upon him is the force of gravity. (Until he lands of course)
