1. Physical quantities and units

Question 1

Physical quantities

Answer 1

all physical quantities consist of a numerical magnitude and a unit

Question 2

Estimating Physical Quantities

Question 3

SI base quantities and units.

What are derived units

what is homogeneity

Answer 3

mass (kg), length (m), time (s), current (A), temperature (K), amount of moles (mol), luminous intensity (candela).

derived units are products or quotients of the SI base unit.

where each term has the same base unit, it is balance and hence homogeneous.

(could be kg=kg or kg=kg+kg for addition and subtraction like s=ut+1/2at^2 is m=m+m and for multiplication & division you multiply or divide the unit simply)

Question 4

prefixes and their symbols to indicate decimal submultiples or multiples of both base and derived units:

Answer 4

pico (p)- 10^-12,
nano (n)- 10^ -9,
micro (μ)- 10^-6,
milli (m) 10^-3,
centi (c)- 10^-2,
deci (d)- 10^-1,
kilo (k)- 10^3,
mega (M)- 10^6,
giga (G)- 10^9,
tera (T)- 10^12

Question 5

explain the effects of systematic errors (including zero errors) and random errors in measurements

Answer 5

Systematic-

Random-

Question 5

distinction between precision and accuracy

Answer 5

precision-

accuracy-

Question 6

assess the uncertainty in a derived quantity by simple addition of absolute or percentage uncertainties

Question 7

difference between scalar and vector quantities and give examples of scalar and vector quantities included in the syllabus

Answer 7

scalar- a quantity with magnitude only.

vector- a quantity with magnitude and direction.

scalar eg-

vector eg-

Question 8

add and subtract coplanar vectors

Question 9

represent a vector as two perpendicular components