Forces Flashcards
What is a vector
a force with magnitude and direction
Give 5 examples of vector quantities
Force, velocity, displacement, acceleration, momentum
What is a scalar
a force with magnitude and no direction
Give 5 examples of scalar quantities
Speed, distance, mass, temperature, time
How are vectors represented
An arrow - the length of the arrow shows the magnitudes and the direction of the arrow shows the direction of the quantity
What is a contact force
When two objects have to be touching for a force to act
Give 3 examples of contact forces
Friction, air resistance, normal contact force
What is a non contact force
If the objects do not need to be touching for the force to act
Give 3 examples of non contact forces
Magnetic force, gravitational force, electrostatic force
What are 2 important effects of gravity
- On the surface of planets it makes all things fall towards the ground
- It gives everything a weight
What is the difference between weight and mass
Mass is a measure of the amount of matter in an object, whereas weight is the force exerted on that object by gravity
What does the weight of an object depend on
The strength of the gravitational field at the location of the object
What is weight measured in
Weight is a force measured in newtons
What is mass measured in
Mass is not a force and is measured in kiilograms
What is the resultant force
The overall force on a point or object
Mass and weight are directly proportional, what is the equation linking them
Weight (N) = mass (kg) x gravitational field strength (N/kg)
What does it mean when an object has been elastically deformed
It can go back to its original shape and length after the force has been removed
What happens when force moves an object
When a force moves an object through a distance energy is transferred and work is done on the object
What does it mean when an object is in equilibrium
All the forces are balanced
What does it mean when an object is inelastically deformed
If it doesnt return to its original shape and length after the force has been removed
What do you need to stretch compress or bend an object
You need more than one force acting on the object, otherwise it would simply move in the direction of the applied force
Extension is directly proportional to force, what is the equation linking them
Force = spring constant x extension
There is a limit to the amount of force you can apply to an object for extension to keep on increasing proportionally
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What do objects in fluids experience
Upthrust
What does it mean when an object floats
It’s weight = upthrust
How does atmospheric pressure change with height
Atmospheric pressure decreases with height
What is acceleration
The change in velocity in a certain amount of time
What is the equation for acceleration
Acceleration = change in velocity / time
What is deceleration
Negative acceleation
On a distance time graph and a velocity time graph what does the gradient represent
Dtg gradient = speed
vtg gradient = acceleration
In which direction does friction act
Opposite direction to movement
What is drag
The resistance you get in a fluid eg air resistance is a type of drag
How can you reduce drag
Keeping the shape of an object streamlined , where the object is designed to allow fluid to flow easily across it reducing drag
How is drag influence by speed
Drag increases as speed increases
What is a terminal velocity
Objects falling through fluids reach a terminal velocity, which is the maximum speed after reaching it it will fall at a steady speed
What is newtons first law of motion
If the resultant force on a stationary object is zero the object will remain stationary. If the resultant force on a moving object is zero it will just carry on moving at the same velocity
What would happen if the force acting on an object is not zero
The object will either accelerate or decelerate in the direction of the force
This acceleration can take five different forms: starting, stopping, speeding up, slowing down and changing direction
What is newtons second law
The acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass of the object
What formula describes newtons second law
Resultant force = mass x acceleration
What is inertia
The tendency for motion to remain unchanged
What is newtons 3rd law
For every action there is an equal and opposite reaction
What is the criteria for newtons 3rd law
-forces have an equal size and opposite direction
- force acts on 2 different bodies
- same type of force
The motion of an object is either
Accelerating
Decelerating
Stationary
Constant speed
