Flashcards in Forces Deck (167):
What happens when a pushing and a pulling force are both exerted on an object?
It can twist
What is the scientific term for a twist?
What can a force do?
It can affect motion
It can change the direction of the movement
It can change the shape of an object
How do you reduce the amount of force needed to move an object?
Reduce the amount of friction
What kind of relationship is there between friction and force?
What is compression?
When a pushing force is applied to both sides of an object
What is changing the shape of an object with forces called?
How do forces affect motion?
What is velocity?
The rate of change of the position of an object
The speed of the object and the direction it is moving
What is a constant velocity?
The same speed in the same direction
What is it called when an object is moving at the same speed?
What is it called when an object moves faster?
What is it called when an object slows down?
What is an agent of motion?
Something that applies a force to another object
What happens when a force is applied to an object?
The object will apply a force that is equal in magnitude and opposite in direction
What is the scientific word for strength?
What does it mean when a force is applied to an object and it does not move?
The object is applying a force that is equal in magnitude and opposite in direction
What happens when two forces are applied to one object?
They combine to make a net/overall force
When you draw force diagrams, what is important?
If a force has a greater magnitude, the arrow line showing the force will be longer
What is a resultant force?
When the net force is greater than 0N
What kinds of forces are there?
Non- contact /field forces
What are the three types of field forces?
What is friction?
The force which opposes motion between substances as they rub against one another
How does friction act?
In the opposite direction of the object that is moving
What is normal force?
The force that pushes back on something that is resting on it
How does normal force act?
Perpendicularly to the object that is resting on the other object
What will the net force of an object sitting on a desk be?
What is the relationship between your weight and mass?
Multiplied by 9.8
Which direction does friction act in?
90° to the force of gravity (weight)
What is a scientific term for weight?
Force of gravity
What surface creates more friction?
What is an applied force?
It moves an object in a specific direction
What is a force of friction?
Opposite direction to movement
What is a force of weight or a force of gravity?
Pulls objects towards an object that has gravity
What is the force of normal?
Solid surface pushes an object up
What is the definition of weight?
The effect of gravity on mass
What does friction depend on?
The type of surface on which an object is moving
What do you need to do to get an object to move?
Overcome the force of friction
Overcome the force of weight
How many Newtons is the force of gravity on Earth?
How do you write net force?
The value of the force
The measurement of the force (Newtons)
The direction of the force
What effect does friction have on the speed of a force?
More friction reduces the speed of an object
Is friction good or bad?
It depends on the situation
When is friction bad?
When it reduces speed
When is friction good?
It helps with grip
What are applied forces?
What kind of force is tension?
A pulling force
What kind of force is compression?
What does a tension force do?
It changes the shape
It stretches an object
What does a compression force do?
Changes the shape
Squashes an object
What applied forces occur in a bridge?
Tension and compression
What does this formula stand for?
Force is equal to mass times acceleration
What is a field?
A ﬁeld is a region in space where an object (with certain properties) will experience a force.
Can field forces touch the object on which they are exerting their force?
They do not have to be touching, but they still work when touching
What is the law of gravity?
Any object that has mass has gravity
What kind of relationship is there between gravity and mass?
What effect does distance have on field forces?
If an object is further away then the force will not be as strong
What are the factors of field forces?
What are the factors of contact forces?
What are the two sides of a magnet called?
What are the two poles of a magnet called?
What force does the North Pole of a magnet exert?
What force does the South Pole of a magnet exert?
One of attraction
What force does Fapplied act with?
How do Fn and Fg act?
How do Fa and Ff work?
What does it mean when forces are balanced?
When two opposing forces ( Fapplied & Ffriction, Fravitational & FNormal) are equal in magnitude and opposite in direction
How can Fapplied = Ffriction?
If an object is moving at a constant speed
What kind of force is gravitational?
What is a force?
A push or a pull on an object
What are forces measured in?
Why do we use Newtons to measure forces?
It is named after Sir Isaac Newton
Who was Isaac Newton?
A mathematician and a physicist
He came up with the three laws of motion
Where do we use forces?
In everything we do
Give examples of how we use forces every single day of our lives?
Our muscles PULL on our bones to make us move
Our feet PUSH on the ground when we walk
We PUSH to open doors
We PULL our food up to our mouths
What does pushing in solid objects do?
It makes them accelerate
What does it mean when an object accelerates?
It gains more speed
What is speed?
It describes how fast an object is moving
What is the definition of acceleration?
It is a measure of how an object's speed changes every second
What is an agent of force?
The thing that applies a force
How do forces act?
What happens to an object when the Fapplied is equal to the Ffriction?
The object will not move
Which direction will an object move?
In the direction of the greater force
What happens when an object exerts a force on another object?
The object pushes back
What was Newton's law about actions and reactions?
For every action, there is are action that is equal in magnitude and opposite in direction
Can more than one force act on an object?
What is net force?
The overall combined force exerted on an object
How do we represent the forces acting on a body?
With free body diagrams
How do we represent forces in a free body diagram?
With vectors (arrows)
How do we represent bodies in free body diagrams?
With a dot
How do we show magnitude in a free body diagram?
By the length of a vector
What kind of force is gravity?
A force of attraction
Where does gravity pull you?
Towards the CENTRE of the Earth
What are the two factors that affect the magnitude of a gravitational force?
How close the objects are
The mass of the object
What is weight actually measured in?
Why is weight not actually measured in kg?
Weight is the effect of gravity on an object
Not the mass in an object
What is the formula for weight?
How do you measure a force?
With a spring balance
How do Spring balances work?
According to Hooke's Law
What is Hooke's Law?
It says that the distance that a spring moves from its resting position is directly proportional to the force that is exerted on the spring
Give four examples of contact forces?
Force of compression
Force of tension
Force of friction
Force of normal
What does friction do to an object?
It resists the movement of an object
What is the relationship between friction and mass?
The greater the mass, the more magnitude the applied force will need to overcome the force of friction
How do you move an object?
You apply a force greater than the force of friction
What is tension?
When an applied force is transferred from one object to another e.g. When a person pulls a rope, which then has tension, the rope pulls the block
What is the difference between tension and compression?
Tension pulls/stretches an object
What are compression forces?
Two forces acting on an object that are opposite in direction (towards one another)
What are tension forces?
Two forces acting in opposite directions (pulling away from one another)
Does repulsion push or pull an object?
Pushes away from itself
Does attraction push or pull?
Pulls toward itself
Where does gravity exist?
Between any two objects that have mass
What relationship do gravity and mass have?
The greater the mass the greater the gravity
What is mass?
The amount of matter in an object
Is weight constant?
Why isn't weight constant?
Mass can change
The magnitude of the force of gravity can change
What is an object on free fall?
An object that only has the force of gravity acting on it
What are magnets?
Objects that have a strong magnetic pull
What do all magnets have?
A North Pole and a South Pole
What are magnetic materials?
Materials that are attracted to magnets
What are the magnetic materials?
What forces do like poles exert on each other?
What forces do unlike poles exert on each other?
What is a magnetic field?
The space around a magnet in which it can exert a force
What are field lines?
Lines in a diagram that represent a force field
How are strong force fields represented?
With field lines that are close together
The more field lines there are, the greater the magnitude of the force
Which way do field lines on a magnet go?
From North to South
Away from North
Does the Earth have a magnetic field?
What is the magnetic field of the Earth like?
There is a North and a South Pole, just like a bar magnet
Where is the magnetic North Pole of the Earth?
At the South Pole
Where is the magnetic South Pole of the Earth?
At the North Pole
How do compasses work?
They respond to the Earth's magnetic field
What are ferrofluids?
Liquids that can become magnetised in the presence of a strong magnetic field
What causes the Northern lights?
Charged particles (from the sun) that escape the belts (areas in Earth's atmosphere that occur because of the magnetic field) and spiral towards the magnetic poles. They then interact with gas particles and cause light shows
What causes static electricity?
Friction between two objects which are being moved
What can friction between two surfaces cause?
Electrons to be transferred
What can happen when electrons jump from one surface to another?
The surfaces' charges could change
What is the type of charge is in a proton?
How are electrons charged?
Where are electrons positioned in an atom?
Around the nucleus
What is the nucleus made up of?
Protons and neutrons
How are neutrons charged?
They have no charge
How is an atom held together?
By electrostatic attraction between the negatively charged electrons and the positively charged protons
How can atoms be neutral?
If the amount of protons and electrons is balanced
When is an object negatively charged?
When it has more electrons than protons
When is an object positively charged?
When it has less electrons than protons
What causes an electrostatic force of repulsion?
When two objects with like charges are brought close together
What causes an electrostatic force of attraction?
When like charges are brought close to each other
What affects the magnitude of an electrostatic force?
Objects that are closer have a greater force
Objects that are more charged have a stronger force
What is an electrostatic discharge?
When extra electrons jump from a negatively charged object to a positively charged object, to balance the charges
What is lightning?
An electrostatic discharge between the clouds and the ground
Who are clouds charged?
Negative on the bottom
Positive on the top
What is thunder?
The sound released during the discharge of electrons from a cloud to the ground
What causes the difference of charges in a cloud?
Friction between particles in the cloud
What is the action? (According to Newton's law)
The force acting on the object
What is the reaction? (According to Newton's law)
The force that the object exerts back in the opposite direction. It will be equal in magnitude
How many forces can act on an object?
More than one
What are contact forces?
forces that act when objects are in contact (touching) with each
Does mass change depending on where you are?
Does weight change depending on where you are?
Yes. If where you are has a different gravitational force, your weight will change
Can magnets work through substances?
Yes, if it is a strong enough magnet
What is free-fall?
When the only force acting on an object is gravitational
Why do astronauts float when in free fall?
Because they are in a spaceship, which is moving at the same speed that they are
What is an alloy?
A mix of more than one metal
What is the relationship between Fapplied and Fweight?
The greater the mass of something the greater the magnitude of force applied to cause motion
What do you need to remember about drawing free body diagrams?
Do not draw the object
Just draw a small circle in the centre
What are vectors?
How does the force of normal compare to the force of gravity?
They are equal in magnitude but opposite in direction