1 Measurements and Uncertainties

Question 1

What are the seven fundamental units?

Answer 1

1. Metre (m)
2. Kilogram (kg)
3. Second (s)
4. Ampere (A)
5. Kelvin (K)
6. Mole (mol)
7. Candela (cd)

Question 3

What is the speed of light written to three significant figures and with scientific notation.

Answer 3

3.00 × 10^8 m s^−1

Question 4

Round off to 3 significant figures

8,46282 m

60,00 m

89,99 s

Answer 4

• 8,46 m
• 60,0 m
• 90,0 s

Question 5

What is the unit of force - as derived unit adn - expressed as fundamental unit

Answer 5

newton (N) Which is derived from the fundamental units: kg m s^−2

Question 6

The radius of a sphere is measured with an uncertainty of 2%.

What is the uncertainty in the volume of the sphere?

Answer 6

When we multiply or divide quantities we add their fractional or percentage uncertainties.

A sphere has 3 dimensions therefore the percentage uncertainties add up to 2+2+2= 6%

Question 7

How do you express speed in fundamental units

Answer 7

m s^-1

Question 8

Write the numbers in standard form. (Scientific notation)

0,000457

88800

Answer 8

4,57 x 10^-7

8,88 x 10^4

Question 9

1. What does SI unit stand for ?
2. What are the two basically different types of units in SI?

Answer 9

1. SI –Système international d’unités.
2. Fundamental Units and Derived Units

Question 10

What are the metric multipliers (prefixes) for A. 10^-3 B. 10^2 C. 10^9

Answer 10

A. milli (used in millimeter for 0,001 meter)

B hecto (used in hectoliter for 100 liter)

C giga (used in gigabyte for 1000000000 byte)

btw.

10^6 is less - megabyte 10^12 is more - terabyte

Question 11

Give the order of magnitude for the following:

A. 840

B. 199

C. The mass of a grown man

D. The mass of a bar of chocolate

Answer 11

The order of magnitude is the size of something to the nearest power of ten, therefore:

A. 10^3 (next to 1000)

B. 10^2 (next to 100)

C. 10^2 (next to 100 kg)

D 10^-1 (100g = 0,1 kg)