Physics Paper 1: Topics 1-6 Flashcards
Equation for distance travelled for an object travelling at a constant speed
Distance travelled (m) = (average) speed (m/s) x time (s) d = s x t
What is the speed of sound in air
340 m/s
What is acceleration, what is meant by uniform acceleration?
Acceleration is how quickly you’re speeding up (change in velocity over time) and uniform acceleration means constant acceleration
Equation for average acceleration
Acceleration (m/s^2) = (final velocity - initial velocity (m/s) ) / time (s)
a = (v-u)/t
What is acceleration due to gravity near earths surface
Roughly 10m/s^2
Equation for uniform acceleration.
Final velocity ^2 (m/s) - initial velocity ^2 = 2 x acceleration x distance
v^2-u^2=2xaxX
On a distance time graph, what does __ tell you:
- gradient at any point (if gradient curved, use a tangent)
- flat
- steeper gradient
- curves
- increasing gradient
- decreasing gradient
- gradient at any point gives the speed of the object
- flat = object has stopped
- steeper graph, object travelling faster
- curves represent acceleration
- increasing gradient, object speeding up
- decreasing gradient, object slowing down
On a velocity time graph, what does __ tell you:
- gradient at any point (if gradient curved, use a tangent)
- flat
- steeper gradient
- positive gradient
- curves
- straight line / and \
- area under graph
Gradient, acceleration
Flat section, steady speed
Steeper graph, greater acceleration or deceleration
Positive gradient, acceleration. Negative gradient, deceleration.
Curve, a changing acceleration
Straight line, / constant acceleration, \ constant deceleration
Area under graph, distance travelled in that time interval
What is Newton’s first law
Resultant force is needed to make something start moving, speed up or slow down, a non zero resultant force always produces acceleration in the direction of the force
What is Newton’s second law
Force and acceleration are directly proportional. Acceleration is inversely proportional to mass of an object.
Equation for resultant force
Resultant Force (N)= mass (kg) x acceleration (m/s^2)
F = m x a
What is equation for weight of an object
Weight (N) = mass (kg) x gravitational field strength (N/Kg)
W = m x g
G = 10 N/Kg on Earth
What is velocity?
Speed and direction of an object
What’s centripetal force?
Force that keeps something moving in a circle. Happens when object moving at constant speed is constantly changing direction, so constantly changing velocity, and so accelerating. Therefore must have a resultant force, which acts towards centre of circle
What’s Inertia? What’s an objects inertial mass?
Tendency for motion to remain unchanged (specifically velocity)
Inertial mass is how difficult it is to change the velocity of the object . The ratio of force over acceleration.
Equation for inertial mass
Inertial mass = force / acceleration
What’s Newton’s third law?
When two forces interact the forces they exert on each other are equal and opposite
Eg book on table: two normal contact forces against each other PLUS Weight due to gravity from Earth vs book pulling back up on Earth
Equation for momentum
Momentum (kg m/s) = mass (kg) x velocity (m/s)
P = m x v
How are changes in momentum caused?
When a resultant force acts on an object for a certain amount of time, it causes change in momentum
Equation for change in momentum
Force (N) = change in momentum (final momentum - initial momentum) (kg m/s) / time (s)
F = (mv-mu) / t
Equation for stopping distance
Stopping distance = thinking distance (affected by drivers reaction time and speed) + braking distance (affected by speed, conditions of breaks etc)
What are the eight energy stores
Kinetic, anything moving
Thermal
Chemical, anything releasing energy through chemical reaction
Gravitational potential, anything in a gravitational field
Elastic potential, anything stretched
Electrostatic, two charges that attract or repel each other
Magnetic, two magnets
Nuclear, atomic nuclei release energy from this store in nuclear reactions
Equation for kinetic energy in an objects kinetic energy store
Kinetic energy (J) = 0.5x mass (kg) x (speed)^2 (m/s^2)
KE = 1/2 x m x v^2
Equation for change in gravitational potential energy in an objects gravitational potential energy stores
Change in gravitational potential energy (J)= mass (kg) x gravitational field strength (N/Kg) x change in vertical height (N/Kg)
Triangle GPE = m x g x triangle h
What are the four main ways of energy transfer between stores
Mechanically: force acting on object and doing work
Electrically: charge doing work against resistance
By heating: energy transferred from hotter to colder object
By radiation: energy transferred by waves
What does it mean when energy is dissipated
Energy is spread out and lost
What is the equation for total energy input
Total energy input = useful energy output + wasted energy
What’s the equation for the efficiency of a device?
Efficiency = useful energy transferred by device (J) / total energy supplied by device (J)
Times answer by 100 to get as a percentage
How does lubrication reduce unwanted energy transfers?
Reduces energy transferred by friction
Explain how conduction works
One side of object heats, particles vibrate more, collide with each other. Energy transferred from particles kinetic energy store to other particles, which then vibrate faster (energy transfers though the object)
What is thermal conductivity
How well a material transfers energy by conduction
What are bio fuels?
Renewable energy resources created from either plant products or animal dung
How does hydro electricity work?
Flooding valleys by building big dams, rain water caught and allowed out through turbines
How do tidal barrages work?
Big dams built across river estuaries with turbines in. Tide comes, fills estuary, water let our through turbines at a controlled speed.
What experiment do you use to investigate motion?
Trolley on ramp test
Can use this to test affect of Trolley’s mass and investigate effects of accelerating force
^ force and acceleration are proportional, mass and acceleration are inversely proportional
What experiment can be used to measure reaction time
Ruler drop experiment
Longer distance ruler falls = longer reaction time
What does a wave do?
I travels through a medium, causing particles in the medium to vibrate and transfer energy and information between each other. Overall, the particles stay in the same place,