PAL (IGCSE) – PHYSICS
Section 1 General Physics
General Physics
PAL (IGCSE) Physics
Revision Book - Section 1
Name: ______
Teacher: ______
Syllabus Content______
Syllabus Details______
1.1 Length and time
Core
• Use and describe the use of rules and measuring cylinders to calculate a length or a volume
THINGS TO REMEMBER...
· Always align your eye with the position being measured
· This avoids parallax errors
• Use and describe the use of clocks and devices for measuring an interval of time
THINGS TO REMEMBER...
· Remember there is always a reaction time associated with using a clock or stopwatch
Supplement
• Use and describe the use of a mechanical method for the measurement of a small distance (including use of a micrometer screw gauge)
· Micrometers are used to measure small distances accurately
• Measure and describe how to measure a short interval of time (including the period of a pendulum)
THINGS TO REMEMBER...
· For measuring short intervals of time (when each period is the same), multiple measurements can be taken and then averaged
e.g. Period of a pendulum = Time for 10 oscillations / 10
1.2 Speed, velocity and acceleration
Core
• Define speed and calculate speed from total distance / total time
Symbol / Definition / SI unit / Vector / ScalarSpeed / v or u / Speed = total distance / total time / m/s / Scalar
• Plot and interpret a speed/time graph or a distance/time graph
• Recognise from the shape of a speed/time graph when a body is
– at rest
– moving with constant speed
– moving with changing speed
• Calculate the area under a speed/time graph to work out the distance travelled for motion with constant acceleration
• Demonstrate some understanding that acceleration is related to changing speed
Symbol / Definition / SI unit / Vector / ScalarAcceleration / a / Acceleration
= change in velocity or speed / time / m/s2 / Vector (for changing v)
• State that the acceleration of free fall for a body near to the Earth is constant
Acceleration of free fall near the Earth is constant
· All objects near the earth fall with a constant acceleration
· The acceleration of free fall is NOT dependent on mass
· The acceleration is ~10m/s2
Supplement
• Distinguish between speed and velocity
Symbol / Definition / SI unit / Vector / ScalarDisplacement / s / Distance moved in particular direction from a fixed point / m / Vector
Velocity / v or u / Velocity = change in displacement / time / m/s / Vector
Speed / v or u / Speed = total distance / total time / m/s / Scalar
Speed has magnitude but no direction - SCALAR
Velocity has magnitude and direction - VECTOR
• Recognise linear motion for which the acceleration is constant and calculate the acceleration
Acceleration is constant if...
· A constant resultant force acts
o Eg.
§ Objects falling in a vacuum
Equations that can be used for constant acceleration...
v=u+at
s=[(u+v)/2]/t
v2=u2+2as
s=ut+1/2at2
s=vt-1/2at2
• Recognise motion for which the acceleration is not constant
Acceleration is NOT constant if...
· A varying resultant force acts
o Eg.
§ Objects falling in air. The air resistance increases with velocity so the resultant force changes
§ A car accelerating. As the velocity of the car increases the air resistance also increases, so the resultant force changes.
• Describe qualitatively the motion of bodies falling in a uniform gravitational field with and without air resistance (including reference to terminal velocity)
1.3 Mass and weight
Core
• Show familiarity with the idea of the mass of a body
• State that weight is a force
• Demonstrate understanding that weights (and hence masses) may be compared using a balance
Supplement
• Demonstrate an understanding that mass is a property that ‘resists’ change in motion
• Describe, and use the concept of weight as the effect of a gravitational field on a mass
· A gravitational field shows a region in which a mass will feel a force due to another mass nearby
· The Earth is a very large mass so a strong gravitational field exists around it
· Weight is the force acting on a mass due to the Earth’s gravitational field
1.4 Density
Core
• Describe an experiment to determine the density of a liquid and of a regularly shaped solid and make the necessary calculation
Supplement
• Describe the determination of the density of an irregularly shaped solid by the method of displacement, and make the necessary calculation
1.5 (a) Effects of forces
Core
• State that a force may produce a change in size and shape of a body
• Plot extension/load graphs and describe the associated experimental procedure
• Describe the ways in which a force may change the motion of a body
• Find the resultant of two or more forces acting along the same line
Supplement
• Interpret extension/load graphs
• State Hooke’s Law and recall and use the expression F = k x
• Recognise the significance of the term ‘limit of proportionality’ for an extension/load graph
• Recall and use the relation between force, mass and acceleration (including the direction)
REMEMBER:
o Acceleration is a vector and so has direction
o Force is a vector and so has direction
• Describe qualitatively motion in a curved path due to a perpendicular force
(F = mv2/r is not required)
1.5 (b) Turning effect
Core
• Describe the moment of a force as a measure of its turning effect and give everyday examples
• Describe qualitatively the balancing of a beam about a pivot
Supplement
• Perform and describe an experiment (involving vertical forces) to show that there is no net moment on a body in equilibrium
• Apply the idea of opposing moments to simple systems in equilibrium
1.5 (c) Conditions for equilibrium
Core
• State that, when there is no resultant force and no resultant turning effect, a system is in equilibrium
FOR A SYSTEM IN EQUILIBRIUM: There is no resultant force and no turning effect
1.5 (d) Centre of mass
Core
• Perform and describe an experiment to determine the position of the centre of mass of a plane lamina
· Hang the lamina freely
· Hang a plum line from the position the lamina is hang from
· Draw a line along the plum line
· Repeat this procedure for another position
• Describe qualitatively the effect of the position of the centre of mass on the stability of simple objects
1.5 (e) Scalars and vectors
Supplement
• Demonstrate an understanding of the difference between scalars and vectors and give common examples
SCALAR / VECTORProperty with magnitude but no direction / Property with magnitude and direction
Example:
Speed
Distance
Pressure
Area
Volume
Work / Example:
Velocity
Acceleration
Force
Displacement
• Add vectors by graphical representation to determine a resultant
• Determine graphically the resultant of two Vectors
1.6 (a) Energy
Core
• Demonstrate an understanding that an object may have energy due to its motion or its position, and that energy may be transferred and stored
Energy...
· cannot be created or destroyed
· can be transferred from one form to another
· can be stored in to be transferred later
• Give examples of energy in different forms, including kinetic, gravitational, chemical, strain, nuclear, internal, electrical, light and sound
Kinetic Energy / Moving objects (Car)
Gravitational Potential Energy / Raised objects (Water in a dam)
Chemical Energy / Energy stored in bonds (coal, oil)
Strain Energy / Energy due to flexing of materials (elastic band)
Nuclear Energy / Energy associated with atomic nuclei (Fission reactors)
Internal Energy / Energy of materials – kinetic from particles moving + potential from bonds
Electrical Energy / Energy from moving charges (electricity)
Light Energy / Energy from Electromagnetic waves (light, IR)
Sound Energy / Energy due to vibrating particles (sound)
• Give examples of the conversion of energy from one form to another, and of its transfer from one place to another
• Apply the principle of energy conservation to simple examples
· For any change to occur in nature energy must be transferred.
· Energy is not created or destroyed it is changed from one form into another
Supplement
• Recall and use the expressions k.e. = ½ mv 2 and p.e. = mgh
1.6 (b) Energy resources
Core
• Distinguish between renewable and non-renewable sources of energy
Non-renewable: Energy sources that when used cannot be replaced (or at least it will take millions of years).e.g. Coal, Oil Natural gas.
Renewable: Energy sources which can be used repeatedly without being used up. Solar energy, Wind, Tidal etc.
• Describe how electricity or other useful forms of energy may be obtained from:
– chemical energy stored in fuel
· Coal can be burnt to release thermal energy - which heats water and makes it move – which turns a generator – which generates electricity
– water, including the energy stored in waves, in tides, and in water behind hydroelectric dams
· Water stored behind a dam or tidal barrier can be allowed to flow down – this moving water turns a generator – which generates electricity
– geothermal resources
· Cold water is pumped underground – the earth warms the water which rises – this moving water turns a generator – which generates electricity
– nuclear fission
· Atoms are split in a nuclear reactor – this releases energy which heats water – the water moves and turns a generator – which generates electricity
– heat and light from the Sun (solar cells and panels)
· Solar energy from the sun can be converted directly into electricity using a solar cell
· Solar energy can also be used to heat water directly (IR)
• Give advantages and disadvantages of each method in terms of cost, reliability, scale and
environmental impact
Energy Source / Cost / Reliability / Scale / Environmental ImpactChemical (Coal) / Low / Reliable / Large / High
Hydroelectric / tidal / High initially / Reliable (unless a drought) / Large / High
Geothermal / High initially / Reliable / Small / Low
Nuclear / High / Reliable / Large / Low
Solar Energy / High / Unreliable (only available during the day) / Small / Low
• Show a qualitative understanding of efficiency
In any energy transfer process energy is “lost” to non-useful forms.
CAR: Chemical Energy is converted to kinetic energy (useful) + Thermal energy (waste)
Supplement
• Show an understanding that energy is released by nuclear fusion in the Sun
NUCLEAR FUSION IN THE SUN
· In the Sun hydrogen nuclei fuse together to form helium nuclei
· In this process energy is released
• Recall and use the equation: efficiency = useful energy output / energy input × 100%
Efficiency = useful output energy / useful input energy
Percentage Efficiency = ( useful output energy / useful input energy ) x 100
· In the transfer of energy from one form into another, there will always be losses, normally to heat energy.
· The efficiency of the process tells use how much useful energy we get and how much is lost
1.6 (c) Work
Core
• Relate (without calculation) work done to the magnitude of a force and the distance moved
Supplement
• Describe energy changes in terms of work done
• Recall and use ΔW = Fd = ΔE
EXAMPLES OF WORK BEING DONE
· A car engine does work against friction and accelerating the car
· When you lift an object you do work against gravity
1.6 (d) Power
Core
• Relate (without calculation) power to work done and time taken, using appropriate examples
Supplement
• Recall and use the equation P = E/t in simple Systems
1.7 Pressure
Core
• Relate (without calculation) pressure to force and area, using appropriate examples
• Describe the simple mercury barometer and its use in measuring atmospheric pressure
· The height of the mercury column relates to the atmospheric pressure
• Relate (without calculation) the pressure beneath a liquid surface to depth and to density, using appropriate examples
• Use and describe the use of a manometer
• Recall and use the equation p = F/A
• Recall and use the equation p = hρg
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