## Numerical Problems on System of Units: Numerical Problems

1. Use standard prefixes used in S.I. system to express following quantities
a) 106 phones b) 10-6 phones c) 1012 cows d) 10-9 monkeys e) 10-12 birds f)12×10-9 dogs g) 34 x 103 boys Numerical Problems
2. Calculate number of kilometers in 20 miles using the conversion factors a mile = 5280 ft, 1 ft = 12 in, 1 in = 2.54 cm, 1 m = 100 cm, 1 km = 1000 m.
3. Calculate the number of light years in one metre.
4. Express 1 parsec in terms of light year Numerical Problems
5. The mass of an electron is 9.1 x 10-31 kg. How many electrons would make 1 kg?
6. The mass of an electron is 9.1 x 10-31 kg. How many electrons would make 1 g?
7. The mass of a proton is 1.67 x 10-27 kg. How many protons would make 1 g?
8. Express the distance between the sun and earth in parsec and light year.
9. Derive the S.I. unit of joule (J) in terms of fundamental units.
10. A new unit of length is chosen such that the speed of light in a vacuum is unity. What is the distance between the sun and the earth in terms of a new unit if it takes 8 minutes and 20 seconds to cover the distance
11. If x = a + bt + ct2, where x is in metres and t is in seconds. Find units of a, b and c.
12. Will the measure of a physical quantity depend on the system of units used?