Estimates #1

Question 1

Physical Constants & Densities

Question 2

What is the density of water?

Answer 2

1 g/cm³ = 1000 kg/m³

Question 3

What is the approximate density of air at room temperature and pressure?

Answer 3

0.5 → 1.5 kg m⁻³

Question 4

What is the estimated density of sand?

Answer 4

2 × 10³ kg m⁻³

Question 5

What is the approximate ratio of densities for solids, liquids, and gases?

Answer 5

1000 : 100 : 1

Question 6

What is the approximate ratio of molecular spacing for solids, liquids, and gases?

Answer 6

1 : 10 : 1000

Question 7

Masses

Question 8

What is the typical mass of a raindrop?

Answer 8

10⁻⁵ kg

Question 9

What is the approximate mass of a car?

Answer 9

1500 kg

Question 10

What is the approximate mass of a bus?

Answer 10

6000 kg

Question 11

What is the mass range of a new pencil?

Answer 11

1 → 20 grams

Question 12

What is the mass range of a protractor?

Answer 12

5 → 50 grams

Question 13

What is the mass range of a plastic 30 cm ruler?

Answer 13

10 → 100 grams

Question 14

What is the mass range of a wooden metre rule?

Answer 14

75 → 120 grams

Question 15

What is the mass of a uranium nucleus?

Answer 15

10⁻²⁵ kg

Question 16

Dimensions & Scales

Question 17

What is the diameter of an atom?

Answer 17

10⁻⁹ → 10⁻¹¹ m

Question 18

What is the diameter of a nucleus (e.g., helium nucleus or alpha particle)?

Answer 18

10⁻¹³ → 10⁻¹⁵ m

Question 19

What is the radius of a fully inflated standard football?

Answer 19

11 cm

Question 20

What is the radius of a tennis ball or cricket ball?

Answer 20

3.5 cm

Question 21

What is the volume of an adult person’s head?

Answer 21

10³ cm³

Question 22

What is the thickness of a sheet of paper?

Answer 22

0.05 → 0.15 mm

Question 23

Pressure, Waves & Electricity

Question 24

What is atmospheric pressure at sea level?

Answer 24

1 × 10⁵ Pa

Question 25

What is the speed of sound in air?

Answer 25

300 → 360 m s⁻¹

Question 26

What is the frequency range of audible sound waves?

Answer 26

20 Hz → 20 kHz

Question 27

What is the range of the Young modulus for materials?

Answer 27

10⁸ → 10¹² Pa (Metals: 10¹⁰ → 10¹² Pa)

Question 28

What is the resistivity of metals?

Answer 28

10⁻⁸ → 10⁻⁶ Ω m

Question 29

What is the standard household voltage supply?

Answer 29

120 / 240 V

Question 30

What is the temperature of a red-hot ring on an electric cooker?

Answer 30

800 °C