physics paper 2 Flashcards
What is a scalar quantity?
A scalar quantity only has magnitude, no direction
What is a vector quantity?
A vector quantity has both magnitude and direction
Name examples of a scalar quantity
Mass, energy, distance, speed, power
Name examples of a vector quantity
Force, acceleration, velocity, momentum, displacement
What is the difference between a contact and a non-contact force?
Contact forces occur due to the contact between two different objects
Noon-contact forces occur due to attraction or repulsion between objects, so there is no contact
Give examples of a contact force
Friction, air resistance, tension
Give examples of a non-contact force
Gravitational force, electrostatic force, magnetic force
How do you calculate the resultant force on an object when two forces are acting in a straight line?
Add their sizes together
How do you resolve a single force into two components acting at right angles to each other?
Split them into vertical and horizontal components
How do you use a vector diagram to determine the resultant of two forces to include both magnitude and direction?
The magnitude and direction of the vector represent the magnitude and direction of the physical quantity being represented. You can add them together to find the resultant forces
What is weight?
A force due to the pull of gravity on an object
What are some factors that can effect weight?
Mass, gravity
Describe the relationship between the extension/compression of an elastic object and the force applied
They are directly proportional
Explain how the work done on a spring and the elastic potential energy are equal
The Work Done on a spring is equal to the change in Elastic Potential Energy of the spring because they are directly proportional
What is work done?
when energy is transferred from one store to another
when a force causes an object to move
Give examples of energy transfers when work is done
Electrical energy -> mechanical energy
Electrical energy -> heat energy
Describe the difference between a linear and non-linear relationship between force and extension
If there is a linear relationship, Hooke’s Law is obeyed
If there is a non-linear relationship, Hooke’s Law is not obeyed
What is the typical value for a person walking?
1.5 m/s
What is the typical value for a person running?
3 m/s
What is the typical value for a person cycling?
6 m/s
What is the typical value for a car on the motorway?
30 m/s
What is the typical value for the speed of sound?
330 m/s
How do you measure the average speed of a moving object?
Dividing the total distance something travels by the total amount of time it spends traveling
On a distance time graph what is the shape of the line for constant speed?
Straight line
On a distance time graph what is the shape of the line for stationary?
Flat, horizontal line
On a distance time graph what is the shape of the line for acceleration?
Curved line going up
On a distance time graph what is the shape of the line for deceleration?
Curved line going down
How do you calculate the speed of an object from a distance-time graph?
Work out the gradient of the line
How do you calculate the acceleration at any particular time on a distance-time graph?
Draw a tangent on the curved line and work out the gradient of that straight line
On a velocity-time graph, what is the shape of a line for constant speed?
Horizontal line
On a velocity-time graph, what is the shape of a line for acceleration?
A straight line that is going up
On a velocity-time graph, what is the shape of a line for deceleration?
A straight falling line
On a velocity-time graph, what is the shape of a line for stationary?
A horizontal line on the time axis
How do you calculate acceleration off a velocity time graph?
Change in velocity/time taken
How do you calculate the distance travelled from a velocity-time graph?
Calculate the area beneath all the different triangles and add them all together
What is stopping distance?
Thinking distance + braking distance
What factors may affect a person’s reaction time?
Age, fatigue, alcohol and drug use
What factors affect braking distance?
The speed of the car, the mass of the car, how worn the brakes are, how worn the tyres are, the road surface
What dangers are created by large decelerations?
The driver may lose control
The brakes may overheat
How do you estimate the forces involved in the deceleration of road vehicles in typical situations, like on a public road?
Braking force x braking distance = 1/2 x mass x (velocity) squared
What is Newton’s first law?
An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force
What is Newton’s second law?
An object will change its velocity in response to a resultant force
F = ma
What is Newton’s third law?
for every action (force) in nature there is an equal and opposite reaction
What is the idea of inertial mass?
The ratio of force over acceleration
It is a measure of how difficult it is to change the velocity of an object
What is the conservation of momentum?
total momentum before an event = total momentum after the event
What are some examples of momentum?
A lorry travelling down the motorway
An elephant walking
How do you calculate momentum?
Momentum = mass x velocity
What is a longitudinal wave?
In longitudinal waves, the vibrations are parallel to the direction of wave travel
What is a transverse waves?
In transverse waves, the vibrations are perpendicular to the direction of wave travel
Name examples of a transverse wave
ripples on the surface of water
vibrations in a guitar string
electromagnetic waves - eg light waves, microwaves, radio waves
Name examples of a longitudinal wave
sound waves
ultrasound waves
seismic P-waves
What is amplitude on a wave?
The distance from the centre line to the peak of the wave or the very bottom of a trough
What is wavelength on a wave?
The distance between two peaks or two troughs
What is wave speed on a wave?
the distance traveled by a given point on a wave in a given interval of time
What is time period on a wave?
The time it takes for one wavelength to pass a specified point
How do you use wave front diagrams to explain refraction in terms of the change of speed that happens when a wave travels from one medium to a different medium?
Showing how wavefronts change direction as they cross the boundary between two media with different speeds.
What is the electromagnetic spectrum, from long to short wavelength
radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
What are some uses of radio waves?
communication such as broadcasting television and radio, communications and satellite transmissions
What are some uses of microwaves?
cooking food, communications and for satellite communications
What are some uses of infrared waves?
electrical heaters, cookers for cooking food, short-range communications like remote controls, optical fibres, security systems and thermal imaging cameras which detect people in the dark
What are some uses of Visible light?
photography and illumination
What are some uses of x-rays?
Low-energy X-rays are used for medical and industrial imaging. High-energy X-rays are used to treat cancer
What are some uses of UV rays?
medical and forensic photography, air purification, disinfection, medical therapy
What are some uses of gamma rays?
sterilising food and medical instruments, and in the treatment and detection of cancer
What is the relationship between wave length, frequency and energy?
As wave length increases, frequency and energy decreases
As wave length decreases, frequency and energy increases
What are the hazardous effects of UV rays?
damage skin cells and lead to skin cancer and damage the eyes, it can cause skin to age prematurely
What are the hazardous effects of x-rays?
Can cause cancer, has harmful effects on skin (increases chances of cells mutating and dividing uncontrollably, leading to skin cancer)
What are the hazardous effects of gamma rays?
Can cause cancer, has harmful effects on skin (increases chances of cells mutating and dividing uncontrollably, leading to skin cancer)
How do different materials cause electromagnetic waves to reflect?
Specular reflection - Reflection from a smooth, flat surface that causes light rays to reflect at the same angle
Diffuse reflection - Reflection on a rough surface that causes light rays to scatter when reflected
How do different materials cause electromagnetic waves to refract?
FAST- Faster - Away / Slower - Towards
How do you construct ray diagrams to illustrate the refraction of a wave at a boundary?
Step 1: Draw a parallel ray on the left
Step 2: Draw the refracted ray at the first surface
Step 3: Draw the refracted ray at the second surface
How do you tell the difference between a permanent magnet and an induced magnet?
An induced magnet only becomes magnetic when placed inside a magnetic field. The induced magnetism is quickly lost when the magnet is removed from the magnetic field
What are some magnetic materials?
Iron
Cobalt
Nickel
Stainless steel
How do the magnetic field lines indicate the strength of the magnetic field?
If the lines are close together the magnetic force is great, if the lines are spread out the force is weak
How do you use a compass to plot the magnetic field around a bar magnet?
place the plotting compass near the magnet on a piece of paper.
mark the direction the compass needle points.
move the plotting compass to many different positions in the magnetic field, marking the needle direction each time.
join the points to show the field lines.
Why does a compass point north?
Earth’s magnetic north pole is near Earth’s geographic south, and they attract
How do you increase the strength of an electromagnet?
increasing current.
increasing the number of turns on the solonoid.
adding an iron core.
How do you use the right hand rule to tell which direction the magnetic field would travel in?
Hold out your right hand with your thumbs tucked in and your thumb pointing upwards: the thumb is equal to the direction of current. the fingers are equal to the magnetic field direction
How do you use Fleming’s left hand rule to predict the force on a wire?
pointer finger in the direction the current is flowing
middle finger in the direction of the magnetic field
and thumb in the direction the wire is pushed
Point the designated fingers in the direction they are meant to go, leaving you with the direction of the force.
What are the factors that affect the size of the force on the conductor?
Current: The larger the current, the larger the force
Length: The longer the length of the conductor, the larger the force
Magnetic Flux Density: The higher the density, the more magnetic field lines and the larger the force on the conductor
How does an electric motor work?
Direct current runs through the wire and experiences a force (the motor effect) exerted on it by the magnetic field. This force causes the coil of wire to turn
