Physics Additional Flashcards
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What are speed and velocity both?
How fast your going
What are speed and velocity both measured in?
M/s or km/h or mph
What is the difference between speed and velocity ?
Speed is how fast your going whereas velocity considers direction and speed
What does the gradient in distance time graphs tell you?
How fast the object is moving - this is because the gradient is she change in y over the change in x = change in distance over the change in time
Hay do flat sections of distance time graphs represent ?
Where the object is stationary
What does a straight line uphill or downhill mean on a distance time graph mean?
The object is moving at a steady speed
On a distance time graph, the steeper the gradient …
The faster the object is going
On a distance time graph, when a line is going downhill this means the object is ..
Travelling back towards its starting point
What do curves on a distance time graph mean?
The object is accelerating or de accelerating
What does a steepening line on a distance time graph mean ?
The object is speeding up
What does a decreasing gradient - levelling off curve mean on a distance time graph ?
The object is slowing down
How do you calculate the speed on a distance time graph ?
Speed = gradient so = vertical over horizontal
What is acceleration?
How quickly velocity is changing
What can a change velocity ?
Change in speed or change in direction or both
What is velocity measured in?
M/s squared
On a velocity time graph what does gradient mean?
Acceleration
On a velocity time graph what do flat sections represent ?
Steady speed
On a velocity time graph, the steeper the graph…
Te greater the acceleration or deacceration
What do uphill sections on a velocity time graph mean?
Acceleration
What do downhill sections on a velocity time graph mean?
De acceleration
How do you work out the distance travelled on a velocity time graph?
The area under the line
What does a curve mean on a velocity time graph ?
A change in acceleration
How do you work out acceleration from a velocity time graph?
Acceleration = gradient = vertical change divided by horizontal change
How do you find the velocity on a velocity time graph?
Reading the value from the velocity axis
What is gravitational force ?
The force of attraction between all masses
What gives everything weight?
Gravitational force
What is the gravitational pull on earth?
10n
What is mass?
The amount of stuff In an object for any given object this will have the same value anywhere in the universe
What is weight?
Caused by the pull of gravitational force in most questions the weight of an onject is just the force of gravity pulling the object to the centre of earth
Would the mass of an object change if it was on the moon or earth?
No an object has the same mass weather it’s on the moon or the earth
Would an object a weight be the same on the moon and earth?
No an object would weigh less on the moon than earth because the gravitational force is pulling it less
What is the gravitational pull on the moon?
1.6 n
How is weight measured?
Newtons -Using a spring balance or newton meter
What is mass measured in?
Kilograms
What is resultant force?
The overall force on a point or object
What does a resultant force cause?
A change in velocity
What does an object need to start moving ?
Force
What would happen if the resultant force on an object was 0?
It would remain stationary
What if there was no resultant force on a moving object?
It would continue to move at the same velocity
What happens when 2 objects hit each other?
The forces they exert on each other are equal and opposite
What does friction always do?
Slows things down
Which direction does friction always act in?
The opposite direction to movement
To travel at a steady speed what does the driving force need to do?
Balance out the frictional forces
What are most resistive forces caused by?
Air resistance or drag
What is the most important factor for reducing drag in fluids?
Keeping the shape of the object streamline
What increases as the speed increases?
Drag or air resistance
What is another word for drag?
Air resistance
What do objects falling through fluids reach?
A terminal velocity
What is terminal velocity ?
The maximum speed an object can move / fall
What causes an object to reach its terminal velocity?
When objects first set off gravity = much more than the frictional force so they accelerate, speed increases causing friction to increase, this gradually reduces acceleration until eventually the frictional force is equal to the acceleration- it will have reached its maximum speed= terminal velocity
What does the terminal velocity of falling objects depend on?
Their shape and area e.g parachute has a large surface area so lots of air resistance
What factors effect stopping distance?
Speed of vehicle- faster = bigger braking force needed. Thinking time = e.g of your going faster you will go further in the few seconds whilst you think. Weather.
How is stopping distance calculated?
The sum {adding} of the braking distance and the thinking distance
Which 4 factors effect braking distance?
How fast your going, quality of brakes, quality of tyres, how good the grip is: depends on 3 things - road surface, weather conditions, tyres.
What happens when a force moves an object through a distance ?
Energy is transferred and work is done
How do you calculate work done?
Force multiplied by distance
What is gravitational potential energy dependant on?
Height of an object
What is kinetic energy?
Energy of movement
How do you calculate kinetic energy ?
A half x mass x speed squared
What does an objects kinetic energy depend on?
It’s mass and speed
What is work done equivalent to?
Kinetic energy
When an object falls what is its potential energy transferred into ?
Kinetic energy
What is work to an elastic object stored as?
Elastic potential energy
What is the extension of an object directly proportional to?
The force acting on it
What does the spring constant of a spring depend on?
It’s material
What does a spring reach when the amount of force you apply causes it to stop extending proportionally
It’s elastic limit
What is power ?
The rate at which energy is transferred
What is a powerful machine ?
One which transfers a large amount of energy in a short space of time
How do you calculate power?
Work done or energy transferred divided by time taken
What is power measured in?
Watts or joules per second. one watt = 1 joule of energy transferred per second
How do you calculate momentum?
Mass x velocity
How is momentum similar to velocity?
It has a value and direction
Momentum ⭐️
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What causes a change in momentum?
When a force acts on the object
The smaller the force acting on an object…
The longer it takes for a change in momentum
Why are cars designed with safety features that slow people down over a longer time when they have a crash?
Because the longer it takes for a change in momentum, the smaller the force acting upon it
What do brakes work against?
The kinetic energy of the car
How do the brakes reduce the kinetic energy of a cat?
They transfer it into heat energy
How do regenerative brakes work?
Instead of transforming the cars kinetic energy into heat, it is transformed into electricity which can charge the vehicles battery
How do crumple zones within cars make crashes more safe?
The cars kinetic energy is transferred into other forms of energy as the car body changes shape, therefore they increase the impact Time decreasing the force produced by the change in momentum
How do side impact bars on a car make crashes safer ?
Strong metal tubes fitted into car door panels they direct the kinetic energy of the crash away from the passengers to other areas such as the crumple zones
How do seat belts make crashes more safe?
As they stretch they increase the time taken for the wearer to stop reducing the forces acting in the chest some of the kinetic energy of the wearer is absorbed by the seat belt stretching
How do air bags make crashes more safe ?
Slow you down more gradually and prevent you from hitting hard surfaces within the car
What determines how powerful cars are?
The size and design of the cars engine
What kind of cars have the highest top speeds?
Ones with a more powerful engine as this means more energy can be transferred per second= more fuel = faster, and cars which are aerodynamic as there is less air resistance
When do cars reach their top speed?
When the resistive force equals the driving force
What was Rutherford’s idea of atomic structure ?
Plum pudding
Alpha particles and plum pudding ⭐️
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