Physics in Chemistry

Question 1

Scalar

Answer 1

A physical quantity that is completely described by its magnitude.

Question 2

Vector

Answer 2

A quantity that has magnitude and direction

Question 3

What is the null vector?

Answer 3

A vector of zero length - it has no direction (represented by a bold zero)

Question 4

What is the centre of mass?

Answer 4

the mass-weighted average of the atomic positions

Question 5

What is the dot product of two orthogonal vectors?

Answer 5

0

Question 6

What is Newton’s First Law?

Answer 6

a body remains at rest or travels at a constant velocity unless a net external force acts on it

Question 7

What is Newton’s Second Law?

Answer 7

the acceleration of a body is proportional to the net force acting on it and inversely proportional to its mass

F = ma

Question 8

What is a newton equal to?

Answer 8

1 N = 1 kg m s ^-2

Question 9

What is Newton’s Third Law?

Answer 9

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

Question 10

What is Newton’s second law in terms of momentum?

Answer 10

Force equals rate of change of momentum

Question 11

What is mechanical work?

Answer 11

when the point at which a force is applied moves in the direction of the force

Question 12

Centripetal Acceleration

Answer 12

the particles acceleration is always towards the centre of the circle

Question 13

What is torque?

Answer 13

the rate of change of angular momentum

• the moment of the force F at a specified point r

Question 14

What is force of a particle in uniform circular motion?

Answer 14

the rate of change of linear momentum

Question 15

What is the law of conservation of angular momentum?

Answer 15

the total angular momentum of a system is conserved if no net external torque acts on it about the same point

Question 16

How to convert 1 GHz to Hz?

Answer 16

1 GHz = 10 ⁹ Hz

Question 17

How to convert 1m to pm?

Answer 17

1 pm = 10 ^-9

Question 18

Define the term angular momentum

Answer 18

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

Question 19

SI units for angular momentum

Answer 19

kg m ² s ^-1 = J s

Question 20

Transverse Waves

Answer 20

the displacement is PERPENDICULAR to the direction of travel of the wave

e.g. electromagnetic radiation

Question 21

Longitudinal Waves

Answer 21

the displacement is PARALLEL to the direction of the wave

e.g. sound waves

Question 22

Superposition Principle

Answer 22

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

Question 22

Standing waves

Answer 22

formed by the superposition of two travelling waves of the same frequency (with the same polarisation and amplitude) travelling in opposite directions.

Question 23

What is an electric field?

Answer 23

the force per unit charge that a particle would experience if placed at a given point

Question 24

What is the electrostatic potential energy?

Answer 24

the energy required to move a charge against the electric field

Question 25

What is the electric potential?

Answer 25

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

Question 26

What is a magnetic field?

Answer 26

the region around a magnetic material or a moving electric charge within which the force of magnetism acts

Question 27

What is a dielectric medium?

Answer 27

an electrical insulator that can be polarised by an applied electric field

Question 28

Lorentz force

Answer 28

the combination of the magnetic and electric force on a point charge due to electromagnetic fields

Question 29

What fundamental constant has the same units as angular momentum?

Answer 29

planck’s constant

Question 30

SI units for torque

Answer 30

e N m = kg m ² s ^-2

Question 31

How to go from GHz to Hz?

Answer 31

1 GHz = 10 ⁹ Hz

Question 32

Define the period

Answer 32

the time taken for a complete turn of 2⫪ radians

Question 33

Define frequency

Answer 33

the number of rotations per unit time