Physics in Chemistry Flashcards
Scalar
A physical quantity that is completely described by its magnitude.
Vector
A quantity that has magnitude and direction
What is the null vector?
A vector of zero length - it has no direction (represented by a bold zero)
What is the centre of mass?
the mass-weighted average of the atomic positions
What is the dot product of two orthogonal vectors?
0
What is Newton’s First Law?
a body remains at rest or travels at a constant velocity unless a net external force acts on it
What is Newton’s Second Law?
the acceleration of a body is proportional to the net force acting on it and inversely proportional to its mass
F = ma
What is a newton equal to?
1 N = 1 kg m s -2
What is Newton’s Third Law?
Action and reactions are equal and opposite.
When one body exerts a force on a second body, the second body exerts a force of equal size and opposite direction on the first body
What is Newton’s second law in terms of momentum?
Force equals rate of change of momentum
What is mechanical work?
when the point at which a force is applied moves in the direction of the force
Centripetal Acceleration
the particles acceleration is always towards the centre of the circle
What is torque?
the rate of change of angular momentum
- the moment of the force F at a specified point r
What is force of a particle in uniform circular motion?
the rate of change of linear momentum
What is the law of conservation of angular momentum?
the total angular momentum of a system is conserved if no net external torque acts on it about the same point
How to convert 1 GHz to Hz?
1 GHz = 10 9 Hz
How to convert 1m to pm?
1 pm = 10 -9
Define the term angular momentum
The moment of the liner momentum p of an object about a specified point : L = r x p, where r is the position of the object relative to the point
SI units for angular momentum
kg m 2 s -1 = J s
Transverse Waves
the displacement is PERPENDICULAR to the direction of travel of the wave
e.g. electromagnetic radiation
Longitudinal Waves
the displacement is PARALLEL to the direction of the wave
e.g. sound waves
Superposition Principle
when two ore more waves simultaneously pass through a point, the disturbance at the point is given by the sum of the disturbances each wave would produce in the absence of the other waves
Standing waves
formed by the superposition of two travelling waves of the same frequency (with the same polarisation and amplitude) travelling in opposite directions.
What is an electric field?
the force per unit charge that a particle would experience if placed at a given point
What is the electrostatic potential energy?
the energy required to move a charge against the electric field
What is the electric potential?
the potential energy change per unit charge for bringing a test charge to a given point from infinitely far away due to an electric field
What is a magnetic field?
the region around a magnetic material or a moving electric charge within which the force of magnetism acts
What is a dielectric medium?
an electrical insulator that can be polarised by an applied electric field
Lorentz force
the combination of the magnetic and electric force on a point charge due to electromagnetic fields
What fundamental constant has the same units as angular momentum?
planck’s constant
SI units for torque
e N m = kg m 2 s -2
How to go from GHz to Hz?
1 GHz = 10 9 Hz
Define the period
the time taken for a complete turn of 2⫪ radians
Define frequency
the number of rotations per unit time
