P2 Flashcards
How do you calculate distance
Speed×time
What are SI units
The agreed set of units used in science
What is a vector quantity
A quantity with both magnitude and direction
What is a scalar quantity
A quantity with magnitude and no direction
What is displacement
The distance from the place you start
What is the difference between speed and velocity
Speed is a scalar quantity, and velocity is a vector quantity
How do multiple (acting together) vector quantities work
If you are given two vector quantities (e.h 2 velocity measurements) you add them together to calculate the total
These quantities will go in a positive direction or negative direction
What is the total velocity of a car traveling to the left at 40mph and a car traveling on the left side of a road, and car traveling on the opposite side of the road at 40mph
They travel in different directions so one is positive and one is negative
-40+40= 0
How are vector quantities shown
We use an arrow to display the direction, and the size of the arrow shows the magnitude
What is acceleration
The change in velocity ÷ change in time
Measured in m/s^2
What does acceleration show
It shows the increase in speed per second.
If something accelerated at 5m/s^2, every second their velocity would increase by 5m/s
How do you use velocities and time to calculate acceleration
Acceleration = (final velocity - initial velocity)÷ time
A = (v-u)÷t
What symbol represents initial velocity
U
What symbol shows final velocity
V
On a distance time graph what does the gradient show
The speed - as distance × time is speed
On a distance time graph what does a horizontal line show
There is no speed - the object is stationary
How do you calculate the gradient
Change in y ÷ change in x
Find two coordinates, subtract the y values and subtract the x values, the divide them
What is the difference between a displacement time graph and a distance time graph
A distance - time graph shows the TOTAL distance travelled, and the gradient is speed
A Displacement - time graph shows how far you have travelled from your original point
It can have a positive or negative gradient
The gradient is velocity
What is a gradient
The degree of steepness on a graph at any point
Also called the slope
What does a velocity time graph show
Acceleration - the gradient
What does a horizontal line mean of a velocity time graph
There is no acceleration, they are moving at a constant speed
How do you calculate distance on a velocity time graph
It is the displacement.
Displacement is the area under the graph
It is calculated by multiplying velocity and speed.
You can find it by working the area out of shapes, then adding them together
On a velocity time graph - how can you tell when something is stationary
If its on the x axis - time increases but there is no velocity
What are SUVAT equations
Equations that can use, displacement, initial velocity, final velocity, acceleration and time to find a missing value (that will be one of the measurements above)
What are the 3 most important SUVAT equations
S= ut+1/2at^2
V^2-u^2 = 2as
V= u+at
What is kinetic energy
The energy associated with a kinetic store
How do you calculate kinetic energy
Ke(J) = 1/2 × mass(KG) × (speed(m/s))^2
Ke = 1/2mv^2
What is Newton’s third law
When body A exerts a force on body B, body B exerts and equal and opposite force on body A
What are non contact forces
A force produced as an object is in a field
The object does not need to be in contact (touching) for the force to act
E.g gravity
How are forces drawn in diagrams
We use a force arrow
As forces are vectors they have magnitude and direction
Ncf arrows’ are drawn from the centre of the object
What are contact forces
The force applied when two objects are in contact ( touching)
E.g pushing a chair
What is an interacting pair
To forces that act upon each other
Examples of contact forces :
Friction - occurs as the atoms that make up two rough surfaces slide over each other
Drag - a force opposite to the direct motion of a body
Upthrust - the force on an object in a fluid dye to a difference in pressure
Tension - solid objects deform slightly when you exert a force on them, and the bonds between the particles are stretched
What does ‘normal’ mean
A force at 90° to the surface of where it hits
A line at 90° to where a wave hits
What is a normal contact force
A contact force that is exerted by a solid surface on an object
Solid objects slightly deform when you exert a force on them, the bonds between particles are compressed
What is the interaction pair on, friction on a sliding box
The force of the box on the surface
The force of the surface on the box
What is a free body diagram
A diagram that shows the forces acting on an object
The object is often represented by a circle and the forces as arrows
What forces do free body diagrams show
ONLY THE FORCES ACTING ON THAT OBJECT
It doesn’t show the forces the object is giving
What is the resultant focre
The total force when two or more forces are added to gather as vectors
(The total strength of the forces acting on an object)
How do you calculate the resultant force, of two forces acting at 90° to each other
Use Pythagoras theorem
A^2+b^2 = c^2
A and be will be the forces that are acting on each other at 90°