Unit 3 Flashcards
What is a scalor quantity
Quantity with size only
Give some examples of scalor quantities
Distance, speed, time, mass, energy, power, temperature
What is a vector quantity
Quantities with magnitude and direction
Give some examples of vector quantities
Displacement, velocity, acceleration, force, weight, momentum
How is magnitude and direction found from a vector diagram
Magnitude - Pythagoras
Direction - trigonometry (SOH-CAH-TOA)
How is velocity of a horizontal vector found
Vcos0
How is force of a vertical vector found
Fsin0
What angle is always used when finding rectangular components of vectors
Angle to the horizontal
When displacement is constant, what do the velocity and acceleration graphs look like?
Both are a straight line at 0 a long the x-axis
When velocity is constant what happens to the displacement on a motion-time graph
Increases
When there is a constant positive acceleration, what does the displacement - time graph look like
Smooth increasing curve ( _/ ) ➡️↗️
When there is a constant positive acceleration what happens to velocity
Velocity increases from zero upwards
When there is a constant negative acceleration what happens to the displacement
Smooth upwards curve ( ↗️➡️ )
How could displacement be found from a velocity-time graph
Area under graph
How could acceleration be found from a velocity-time graph
Gradient of line
How would velocity be found from a velocity time graph
Value from best fit line
How would displacement be found from a displacement-time graph
Value from best fit line
How would velocity be calculated from a displacement-time graph
Gradient of line
How would acceleration be found from a displacement-time graph
Calculate from velocity values, a = v-u/t
What indicates a change in direction on a velocity-time graph
Crossing the x-axis
Define acceleration
Change in velocity per second
From the equation a + v-u/t what does the u and v represent
u = starting velocity v = final velocity
What experiment can be used to find the acceleration of an object
Measured using a trolley with a mask(s) and light gate (s)
What measurements would need to be made when measuring acceleration
- length of mask
- time through light gate(s)
- time between light gates or time between masks
What is Newton’s first law of motion
An object will remain at rest or continue in at a constant speed unless acted on by an unbalanced force
What is Newton’s second law
An unbalanced force will cause an object to accelerate
In what direction does friction act relative to the object
In the opposite direction
How can the unbalanced force be calculated
F = Fh - Ffric
What is tension
The pulling force acting on a cable
When a lift is stationary or moving at a constant speed are the forces balanced or unbalanced
Balanced
When are the forces unbalanced in a lift
When the lift is accelerating or decelerating
When is the value for ‘a’ in the equation T = mg + ma positive
Accelerating up or decelerating down
When is the value for ‘a’ negative
Accelerating down or decelerating up
In the rocket example of vertical thrust when are the forces balanced
When rocket is stationary
Why does a rocket acceleration increase
Mass decreases - fuel used up
Weight decreases - acceleration due to gravity decreases
Air less dense - air resistance decreases
How is Wpara calculated
Wpara = mgsin(angle)
How is Wperp calculated
Wperp = mgcos(angle)
How is the force calculated if the object is moving up a slope
F = Wpara - Ffric
When is the equation F = Wpara + Ffric used
When an object is moving up the slope
Define work done
Amount of energy transferred from one place to another
What is power
The amount of energy transferred per second