Forces Flashcards
What is a scalar quantity?
Magnitude
What is a vector quantity?
Magnitude + direction
What is a force?
Something that occurs when two or more objects interact
What quantity is a force?
A vector quantity
What are the 2 types of force?
Contact
Non-contact
What does a contact force involve?
Touching objects
What does a non-contact force involve?
Objects that are not touching
What is gravity?
A force of attraction between all masses
What is mass?
The amount of matter an object contains
What is weight?
The force that acts on an object due to gravity
What is a resultant force?
When more than one force acts on an object but has the same effect as all the forces acting together
What is a free body diagram?
The diagram that can be used to show different forces acting on an object
What happens when a force causes an object to move?
Work is done
What happens when work is done?
Energy transfers take place within the system
What does elastically deformed mean?
When an object returns to its original shape after a force is removed
What does inelastically deformed mean?
When an object does not return to its original shape after a force is removed
What is the extension of an object directly proportional to?
The applied forced
What happens once the limit of proportionality has been exceeded?
Doubling the force will no longer exactly double the extension
The relationship becomes non-linear
A force-extension graph will stop being a straight line
What does the spring constant indicate?
How easy it is to stretch or compress a spring
What is the turning effect called when a force causes an object to rotate around a pivot point?
Moment of a force
What can levers and gears be used for?
Transmit the rotational effects of forces
Magnify either the size of the applied force or the distance the force moves over
What state can a fluid be?
Liquid or gas
What happens as particles move around in a fluid?
They collide with the surface of objects in the fluid or the surface of the container
What force do the collisions of particles in a fluid make?
A force normal (at right angles) to the surface
What is the atmosphere?
A relatively thin layer of air around the Earth
What happens if the altitude is great?
The atmosphere is less dense and the atmospheric pressure is lower
What does pressure at a particular point in a column of liquid depend on?
The height of the column above the point
The density of the liquid
What happens if the column is higher and the liquid is more dense?
The greater the weight above the point
The greater the force on the surface at that point
The greater the pressure
What is upthrust?
The force exerted by a fluid on a submerged object
When do objects float?
When its weight is equal to the upthrust
When do objects sink?
When the weight is greater than the upthrust
What indicates if an object will float or sink?
The density
What does an object less dense than liquid do?
Displaces a volume of liquid greater than its own weight so it will rise to the surface
Will float with some of the object remaining under the water
Displaces liquid of equal weight to the object
What quantity is distance?
Scalar
What is distance?
How far an object has moved
It does not need to take into account the direction the object is moving in
What quantity is displacement?
Vector
What is displacement?
It has a magnitude, which describes how far the object is from its origin
What is the speed of an object?
The measure of how fast an object is travelling
What quantity is speed?
Scalar
What quantity is velocity?
Vector
What is velocity?
The speed of an object in a given direction
What does an object moving in a straight line with a constant speed also have?
A constant velocity
What happens if an object is not moving in a straight line?
The speed can still be constant
The velocity will be changing, because the direction has changed
Describe an object moving in a circle.
Is constantly changing direction, so it is constantly changing velocity
Is accelerating even if travelling at a constant speed
What is Newtons first law?
An object will remain in the same state of motion unless acted on by an external force
What happens to an object when the resultant force acting on it is zero?
If the object is stationary, it remains stationary
If the object is moving, it continues to move at the same speed and in the same direction
What do distance-time graphs represent?
Represent the motion of an object acting in a straight line
What will the distance-time graph show if the object is accelerating?
A curve
What is acceleration of an object?
A measure of how quickly it speeds up, slows down or changes direction
What can the gradient of a velocity-time graph be used to find?
The acceleration of an object
What is Newton’s 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 happens when an object falls through a liquid?
At first, the object accelerates due to the force of gravity
As it speeds up, the resistive forces increase
The resultant forces reach zero when the restrictive force balances the force of gravity. At this point the object will fall at a steady speed called its terminal velocity
What is Newtons third law?
For every action there is an equal and opposite reaction
What do all moving objects have?
Momentum
What happens when an unstable force acts on an object that is moving or unable to move?
A change in momentum occurs
What happens to momentum in a closed system?
The total momentum before an event is equal to the total momentum after the event
What does the stopping distance of a vehicle depend on?
Thinking distance
Braking distance
What is thinking distance?
The distance travelled during the drivers reaction time
What is braking distance?
The distance travelled under the braking force
What can affect reaction time?
Tiredness, distractions, drugs and alcohol
What factors could affect braking distance?
Conditions of the road, conditions of the vehicle and the weather
