Questions
SI Units and Prefixes
1.
What is the base unit for the amount of a substance?
2.
Is a newton a base unit?
3.
What is the kilogram a base unit for?
4.
How would you express 1 hour in SI Units?
5.
List all SI units
6.
How would you express temperature in terms of SI Base Units?
7.
Is a joule an SI unit?
8.
V=IR, which quantity has an SI Base unit?
9.
Express the following derived units in terms of SI Base units.
10.
a)
Newton, N
b)
Pascal, Pa
c)
Watt, W
The following equation may be used to calculate the force between two masses:
F=
G m1m 2
r2
Where:
•
G is a constant of value: 6.674x10−11kg −1m 3s −2
•
m1 and m 2 are the masses of each object, in kilograms
•
r is the distance between the centre of mass of each object, in metres.
Express each side of this equation in terms of SI Base units. Hence, check the homogeneity of this equation.
Questions Continued
SI Units and Prefixes
11.
12.
Convert the following quantities to base units: (e.g. metres, seconds, kilograms, etc)
a)
50,000m
b)
7400kg
c)
0.0000354A
d)
8600 minutes
Use the correct prefix to write the following quantities in the shortest form:
a)
85,000,000J
b)
0.000004m
c)
7650s
d)
0.008V
13.
Express 35eV in J.
14.
Express 54MJ in kW h.
15.
Estimate the mass of an average elephant, in kilograms.
16.
Estimate the pressure felt if an elephant were to stand on your foot!
17.
Estimate the height of the Eiffel Tower, in metres.
18.
Estimate how long it would take a ball to fall from the top of the Eiffel Tower.