01 Working As A Physicist

Question 1

Define acceleration

Answer 1

The rate of change of velocity

Question 2

How to get uncertainty

Answer 2

Range / 2

Question 3

What is the difference between a base unit and a derived unit?

Answer 3

A base unit is one of seven fundamental units. A derived unit is derived by the multiplication or division of units.
A unit is a measure of quantity, such as distance, mass and time.

Question 4

What is the order of the scale units?

Answer 4

Femto [10^-15] ->Pico [10^-12] -› Nano[10^-9] -> Micro [10^-6] -> Milli [10^-3] -> Centi [10^-2] -> Deci [10^-1] -> Kilo [10^3] - Mega [10^6] -> Giga [10^9] -> Tera [10^12]

Question 5

What is the difference between independent and dependent variables?

Answer 5

• Independent variables are what you change in an investigation. Dependent variables are what is observed or measured.
  • Independent variables are normally the cause of the effect on the dependent variables.

Question 6

What is the difference between precision and accuracy?

Answer 6

Precision is determined by the consistency of results; a measurement is precise if the values ‘cluster’ closely together. It is influenced by random errors.

Accuracy is determined by how close the measurement is to the true value; a measurement is accurate if it is close to the true value. It is influenced by random and systematic errors.

Question 7

What is the difference between error and uncertainty?

Answer 7

• Error is the difference between the measurement and the true value.
• Uncertainty is the interval within which the true value can be considered to lie with a given level of probability. It is determined by apparatus and variables.

Question 8

How do you work out percentage uncertainty?

Answer 8

Percentage uncertainty =absolute uncertainty / actual or average reading ×100

Question 9

What is the difference between repeatable and reproducible?

Answer 9

Measurements are repeatable when similar results are obtained from by students from the same group using the same method.
Measurements are reproducible when similar results are obtained by students from different groups using different methods or apparatus.

Question 10

How can the validity of results be improved?

Answer 10

• Control more variables
• Use more precise measuring equipment
• Obtain more results to reduce uncertainty

Question 11

What is the difference between random and systematic error?

Answer 11

• Random errors are caused by unpredictable changes in the investigation, often caused by the environment or irregular changes. This usually affects the precision.
• Systematic errors are continuous errors throughout the investigation, and are usually caused by limitations in equipment e.g. zero error. This usually affects the accuracy.

Question 12

What are all the base units, their symbols, their unit and their base unit

Answer 12

Time - t - s - second
Length - L - m - metre
Mass - m - kg - kilogram
Temperature - T - k - kelvin
Current - I - A -amperes
Amount of substance - n - (no unit) - mole

Question 13

SA off a sphere equation

Answer 13

4πr²

Question 14

Sphere volume equation

Answer 14

4/3πr^3

Question 15

Define velocity

Answer 15

The rate of change of displacement : measured in ms^-1

Question 16

Define speed

Answer 16

The rate of change of distance

Question 17

How do you convert cm^2 to m^2

Answer 17

xcm^2 / 100^2
It is 100 because there are 100cm in a metre

Question 18

How do you convert m^2 to cm^2

Answer 18

xm^2 x 100^2

Question 19

How do you convert m^3 to cm^3

Answer 19

xm^3 x 100^3

Question 20

How to convert km^2 to m^2

Answer 20

xkm^2 x 1000^2

Question 21

4km^2 to m^2

Answer 21

4 x 1000^2 = 4,000,000

Question 22

How to convert 1km/h to m/s

Answer 22

(1 x 1000) / 3600 (amount of seconds in an hour) = 0.28m/s

Question 23

Convert 5km/h to m/s

Answer 23

5 x 1000 / 3600 = 1.4m/s

Question 24

Convert 5m/s to km/h

Answer 24

5 x 3600/ 1000 = 18 km/h
Or 5 / (1000 / 3600 )

Question 25

10 m/s in km/h

Answer 25

10 x 3.6 = 36km/h