Physics A2 Level

Card Set Information

 Author: koolcookie11 ID: 122655 Filename: Physics A2 Level Updated: 2011-12-15 04:48:21 Tags: physics alevel key words Folders: Description: Key Words Unit 4 Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user koolcookie11 on FreezingBlue Flashcards. What would you like to do?

1. Force
rate of change of momentum
2. Momentum
mass times velocity
3. Newton's laws of motion
• First law: an object continues at rest or in uniform motion unless it is acted on by a resultant force
• Second law: the rate of change of momentum of an object is proportional to the resultant force on it
• Third law: when two objects interact, they exert equal and opposite forces on one another
4. Newton's law of gravitation
the gravitational force F between two point masses m1 and m2 at distance r apart is given by F=Gm1m2/r2
5. Impulse
force times time for which the force acts on an object
6. Principle of conservation of momentum
when two or more bodies interact, the total momentum is unchanged, provided no external forces act on the bodies
7. Conservation of momentum
for a system of interacting objects is the total momentum of the objects remains constant provided no external resultant force acts on the system
8. Kinetic energy
the energy of a moving object due to its motion
9. Explosion
when two objects fly apart, the two objects carry away equal and opposite momentum
10. Elastic collision
a collision in which the total kinetic energy after the collision is equal to the kinetic energy before the collision
11. Uniform circular motion
motion of an object moving at a constant speed along a circular path
12. Angular displacement
the angle an object in circular motion turns through
13. Angular speed
the rate of change of angular displacement of an object in circular motion
14. Centripetal acceleration
for an object moving at speed v in uniform circular motion its centripetal acceleration a=v2/r towards the centre of the circle
15. Centripetal force
the resultant force of an object that moves along a circular path
16. Equilibrium
state of an object when at rest or in uniform motion
17. Amplitude
the maximum displacement from equilibrium of an oscillating object
18. Displacement
distance in a given direction
19. Free oscillations
oscillations where there is no damping and no periodic force acting on the system so the amplitude of the oscillation is constant
20. Time period
time taken for one complete cycle of oscillations
21. Frequency
the number of cycles of oscillation per second
22. Angular frequency
for an object oscillating at frequency f in simple harmonic motion its angular frequency = 2pif
23. Phase difference
24. Simple harmonic motion
motion of an object if its acceleration is proportional to the displacement of the object from equilibrium and is always directed towards the equilibrium position
25. Dissipative forces
forces that transfer energy which is wasted
26. Damped oscillations
• oscillations that reduce in amplitude due to the presence of resistive forces such as friction and drag
• 1.Lightly damped system: amplitude of oscillations decreases gradually
• 2.Heavily damped system: the system slowly returns to equilibrium without oscillating
• 3.Critically damped system: system returns to equillibrium in the least possible time without oscillating
27. Periodic force
a force that varies regulary in magnitude with a definite time period
28. Natural frequency
the frequency of free oscillations of an oscillating system
29. Forced oscillations
oscillations of a system that is subjected to an external periodic force
30. Resonance
the amplitude of vibration of an oscillating system subjected to a periodic force is largest when the periodic force has the same frequency as the resonance frequency of the system
31. Resonant frequency
the frequency of an oscillating system in resonance
32. Gravitational field
the region surrounding an object in which it exerts a gravitational force on any other object
33. Line of force/ Field line
a line followed by a, small mass in a gravitational field/ a small positively charged object in an electric field/ a free north pole in a magnetic field, acted on by no other forces than the force due to the field
a field in which th field lines are straight and converge or diverge as if from a single point
35. Uniform field
a region where the field strength is the same in magnitude and direction at every point in the field
36. Gravitational potential
the work done per unit mass to move a small object from infinity to that point in a gravitational field
37. Gravitional potential energy
the work done to move a small object from infinity to that point in the field
• at a point in a field is the change of potential per unit charge of distance along the field line at that point
• -the field strength at any point
39. Gravitational field strength
the force per unit mass on a small mass placed in the field
40. Gravitational force
an attractive force that acts equally on any two objects due to their mass
41. Kepler's third law
for any planet, the cube of its mean radius of orbit is directly proportional to the square of its time period
42. Universal constant of gravitation/ Gravitational constant
the constant of proportionality in Newton's law of gravitation
43. Electrical conductors
an object that can conduct electricity
44. Free electrons
electrons in a conductor that move about freely inside the metal because they are not attached to a particullar atom
45. Gold leaf electroscope
a device used to detect electric charge
46. Insulating materials
a material that cannot conduct electricity
47. Electric field strength
the force per unit charge on a small positively charged object at a point in an electric field
48. Electric potential
the work done per unit charge on a small positively charge object in an electric field to ove it from infinity to that point in the field
49. Equipotentials
a line or surface in a field along which the electric or gravitational potential is constant
50. Coulomb's law
• for two point charges Q1 and Q2 at distance apart r, the force between the two charges
51. Capacitance
• the charge stored per unit pd of a capacitor
• unit- farad (F)= 1 coulomb per volt
52. Time constant
the time taken for a quantity that decreases exponentially to decrease to 0.37 (=1/e) of its initial value
53. Capacitor energy
energy stored by the capacitor
54. Capacitor discharge
through a fxed resistor of resistance R, time constant= FC
55. Motor effect
the force on a current-carrying conductor due to a magnetic field
56. Fleming's left-hand rule
rule that relates the directions of the force, magnetic field and current on a current-carrying conductor in a magnetic field
57. Magnetic flux density
the magnetic force per unit length per unit current on a current carrying conductor at right angles to the field lines
58. Simple electric motor
an electric motor with an armature consisting of a single coil of insulated wire
59. Hall probes
a device used to measure magnetic flux density
60. Magnetic force
61. Electromagnetic induction/ Induced emf
the generation of an emf when magnetic flux linkage through a coil changes or a conductor cuts across magnetic field lines
62. Fleming's right-hand rule/ Dynamo rule
rule that relates the directions of the induced current, magnetic field and velocity of the conductor when the conductor cuts across magnetic field lines and an emf is induced in it
63. Lenz's law
when a current is induced by electromagnetic induction, the direction of the induced current is always such as to oppose the change that causes the current
64. Magnetic flux
equals BA for a uniform magnetic field of flux density B that is perpendicular to an area A
through a coil of N turns, = NBA
66. Faraday's law of electromagnetic induction
the induced emf in a circuit is equal to the rate of change of magnetic flux linkage through the circuit
67. Transformer
• converts the amplitude of an alternating pd to a different value
• it consists of two insulated coils, the primary and secondary coil, wound round a soft iron laminated core
68. Step-up transformer
a transformer in which the rms pd across the secondary coil is less than the rms pd applied to the primary coil
69. Step-down transformer
a transformer in which the rms pd across the secondary coil is greater than the rms pd applied to the primary coil
70. Transformer rule
the ratio of the secondary voltage to the primary voltage is equal to the ratio of the number of secondary turns to the number of primary turns
71. Transformer Efficiency
for an ideal transformer the output power equals the input power
72. Eddy currents
unwanted induced currents in the metal parts of ac machines
73. National Grid System
the network of transformers and cables that is used to distribute electrical power from power stations to users
74. Back emf
• emf induced in the spinning coil of an electric motor or in any coil which the current is changing
• acts against applied p.d.

What would you like to do?

Home > Flashcards > Print Preview