P1A , P1B, P1C (physical quantities, motion & mass weight density) Flashcards
Average speed formula- why?
Total distance/Total time
becayse speed is not constant throughout
Scalar
-Speed
-Distance
-Time
Vector
-Velocity
-Displacement
-Accelaration
vector
takes into consideration direction
scalar
magnitude
Acceleration
Rate of change of velocity
formula for acceleration
change in velocity/change in time
calculate the average speed of a motor car that travels 500 meters in 20 seconds.
25m/s
what formula is used to calculate speed?
Speed= Distance/time
Difference between speed and velocity
Speed is simply the rate at which an object covers a distance (scalar)
While Velocity measures speed in a specific direction. (vector)
What does a minus or plus sign mean with velocity
- = Going the opposite direction
+ = moving in the positive direction. (right or up or left or down depends on the context)
What does a straight line on a DT graph mean
That the object has paused
What does a curve mean on a DT graph
acceleration
what does diagonal straight incline mean on DT
Constant speed
What is acceleration
Acceleration is the rate at which an object’s velocity changes over time.
How is acceleration shown on a DT graph
A smooth curve
how can acceleration be calculated
change in velocity/time taken
Horizontal line on a VT graph
steady speed
Straight diagonal line on a VT graph
steady acceleration
Curve on a VT graph
A curve on a VT graph indicates changing acceleration
How do you find distance from a VT graph
The area under a VT graph gives the distance because Distance =speed x time
(make sure unit is consistent)
What happens when you drop an object
Gravity acts on the object and causes it to accelerate.
This acceleration of free fall g is constant for a body near the earth, acts downwards and has a value of approximately 9.8m/s^2
unit for acceleration
m/s^2
How can you tell from a distance time graph whether the object is moving away from you or toward you?
If the distance is increasing (the graph slopes upward), the object is moving away from you.
If the distance is decreasing (the graph slopes downward), the object is moving toward you.
Acceleration
The rate (how quickly) of change of velocity.
Acceleration formula
change in velocity/ time taken
a= (v-u)/t
v= final velocity in m/s
u= starting velocity in m/s
t= time taken s
calculate the acceleration of a car that travels from 0m/s to 28 m/s in 10 seconds
2.8m/s^2
As a stone falls it accelerates from 0m/s to 20m/s in 2 seconds. calculate its acceleration and state unit.
10m/s^2
A racing car slows down from 45m/s to 0 m/s in 3 seconds. Calculate the acceleration
-15m/s^2- final velocity=0 - initial velocity 45 -45/3= -15
How do you calculate acceleration from a speed time graph
the gradient of a speed-time graph
How do you find distance from a speed-time graph
the area beneath the graph
always make sure the units are consistent
Two runners complete a 400m race. Athlete A takes 50s and athlete B takes 64s
calculate the average speed of each runner
8m/s and 6.25 m/s
What is the vector version of these:
-speed
-distance
-velocity
-displacement
What does a steep slope on a distance-time graph represent?
The object is moving quickly. The steeper the slope, the faster the object is moving.
How can you determine the speed of an object from a distance-time graph?
Speed is the gradient (slope) of the line. A steeper slope means a higher speed.
What does a curved line on a distance-time graph mean about the object’s motion?
The object’s speed is changing, meaning it’s either accelerating or decelerating.
What does a horizontal line on a velocity-time graph represent?
The object is moving at a constant velocity.
What does a negative slope on a velocity-time graph suggest?
The object is decelerating (slowing down).
What does a horizontal line on a velocity-time graph represent?
The object is moving at a constant velocity.
Mass (scalar)
How much material is present in the object (g,kg etc.)
Weight (vector)
force on the object due to gravity (N)
velocity
rate of change of displacement (distance travelled) (m/s)
Weight formula
m (mass) x g (gravitational field strength)
gravitational field on earth
9.8
mass is a property that _____ change in motion
resists
how do you find the mass of something?
The most accurate way is with a balance.
The balance is level when the forces pulling down both sides are the same.
How do you find the weight of something?
A spring balance:
-The top of the spring is hung from a hook
-The scale can then be adjusted so that the pointer is aligned
Gravity is an _____ , _______ force
attractive, non contact
What is gravitational force
acceleration due to gravity
why does a heavier object fall faster than a lighter object
due to air resistance or water resistance
Terminal velocity
The constant speed that a falling object reaches because the force of gravity is balanced by air resistance.
field strength
N/kg
what is density
how much mass is in 1m^3 or 1cm^3 of an object
formula for density
ρ=m/v.
mass/volume.
density of water
1g/cm^3
what happens when the density of an object is less than the fluid
it floats
what happens when the density of an object is more than the fluid
it sinks- upthrust is less than weight
what happens when objects fall in a vacuum
there is no air resistance or liquid resistance so the only force acting on them is the force of weight.
what is a vacuum
space that contains no matter
force formula
mass x acceleration
What is upthrust
the force that pushes upwards on an object submerged in a liquid.
what direction does upthrust always act in
opposite direction to the object’s weight force
The ________ the object the _________ the upthrust
denser greater
what does an object floating say about the upthrust
it is equal to the weight.
what does the size of upthrust depend on
the density of the fluid
The volume of fluid pushed aside (equal to the volume of the object)
how do you calculate the density of a regularly shaped object
- Measure the mass:
Use a balance or scale to find the object’s mass in kilograms (kg) or grams (g).
- Find volume by finding length, width, height
mass/volume
how do you calculate the density of an irregularly shaped object
- measure mass
- measure volume- measure the original volume of water then
- submerge the object in the water completely, ensuring it’s fully underwater
4.Measure the new water level. The increase in water level shows the volume of the object. Final water level - Initial water level
- mass/volume
what can be certain flaws in calculating the density of an irregularly shaped object
-The water level may not be read accurately.
-The object might not be fully submerged, leading to incorrect displacement.
what does resultant force= 0 look like on a vt graph
horizontal line- acceleration=0
