AS物理概念大全
2016版
Unit1&2
#velocity is the rate of change of displacement.
#acceleration is the rate of change of velocity.
#displacement is the distance traveled in a particular direction.
Unit3
#Newton’s first law:
an object will remain at rest or in a state of uniform motion unless it is acted on by an external force.
电工常识#Newton’s cond law:
With the object’s mass constant,acceleration produced is directly proportional to the force applied.
对联横批大全
#Newton’s third law:百家姓所有姓氏
when two bodies interact,the forces they exert on each other are equal in magnitude and in opposite direction.
#weight is the pull by gravitation.
Unit4
#moment of a force:
force×perpendicular distance of the pivot from the line of the action of the force.
#torque of a couple:
one of the forces×perpendicular distance between the forces.
#for an object to be in equilibrium:
1.the resultant force acting on the object is0
2.the resultant moment is0.
#vectors:both have direction and magnitude.
qq农场吧#scalars:only have magnitude.
Unit5
#work done=force×the distance moved in the direction of the force. #principle of conrvation of energy:
for a clo system,energy cannot be destroyed or created by itlf,it can be transferred to other forms,but the total amount of energy remains constant.
#power is the rate at which work is done(or energy is transferred). Unit6
#momentum=the product of mass and velocity.
#the principle of conrvation of momentum:
for a clod system,in any direction,the total momentum before the interaction in equal to the total momentum after the interaction.
#elastic collision:the total kinetic energy is conrved.
#inelastic collision:the total kinetic energy is not conrved.
#net force=the rate of change of momentum.
(F=△P/△t)
Unit7
#density:mass per unit volume.
#pressure=normal force/cross-ctional area.渲图
十二月的奇迹Unit8
#Hooke’s law:the extension of a material is directly proportional to the applied force as long as it’s elastic limit is not exceeded(F=kx). #elastic limit point:the point beyond which the material doesn’t return back to its original shape when the load is removed.
#stress:force/cross-ctional area(σ=F/A)[unit:Pa]
范例教学#strain:extension/original length(ε=x/L)
#Young modulus=stress/strain(E=σ/ε)[unit:Pa]
Unit9
#electric filed strength:the electric force acting per unit positive charge at a point in the field(E=F/Q).
Unit10藏族图案
#current:the rate of flow of charge(I=Q/t).
#charge=current×time(Q=It).
#potential difference:the potential difference between two points,A and B,is the energy given up by unit charge as it moves from point A to point B.
#e.m.f.:the total work done when unit charge goes round a complete circuit.
#resistance=voltage/current.
#electric power=current×potential difference(P=IV)
Unit11
#Kirchhoff’s first law:
The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving the point.
#Kirchhoff’s cond law:
The sum of f.s around any loop in a circuit is equal to the sum of the p.d.s around the loop.
Unit14
#amplitude:the maximum displacement of any point on the wave from its undisturbed position.
#wavelength:the distance from any point on a wave to the next exactly similar point.
#period:the time taken for one complete oscillation of a point in a wave.
#frequency:the number of oscillations per unit time of a point in a wave.
#longitudinal wave:the particles of the medium vibrate parallel to the direction of the wave velocity.
#transver wave:the particles of the medium vibrate at right angles to the direction of the wave velocity.
#intensity of a wave:power/cross-ctional area.
Unit15
#principle of superposition:
When two or more waves meet at a point,the resultant displacement is a algebraic sum of the displacements of the individual waves.
#diffraction of waves:the spreading of a wave as it pass through a gap or around an edge.
Unit16
#progressive wave:starting from the source and travel outwards, transferring energy from one place to another.
#stationary wave:incident wave and reflected wave traveling in opposite directions meet and superimpo.
Unit17
#α-particle scattering experiment
mostα-particles have little or no deviation(most of an atom is empty space).
a very fewα-particle are deviated more than900(most of the mass of an atom is concentrated in a small space).
#isotopes:the element that with the same number of protons but different number pf neutrons.
#mass-energy conrvation:the mass is converted into energy and relead out,the mass and energy is conrved.
