|
Expermental Physics Tutorial: Science is all about experiments, all the hypothesis become a law only if they are justified experimentally. Experimentation involves lots of terms like accuracy, precision etc. and all the observations and corresponding values obtained are merely approximate, however the level of approximation depends upon the appartus. In this unit we will explore all about errors and then and then move on to another powerful tool called dimensional analysis. while closing the chapter we look at few experiment that are used to determine few physical quantities.
Unit Conversion Table:
Length:
1 in = 2.54 cm
1 m = 39.37
1 ft = 39.37 in. = 3.281 ft
12 in = 1 ft
3 ft = 1 yd
1 yd = 0.9144 m
1 km = 0.621 mi
1 mi = 1.609 km
1 mi = 5280 ft
1  = 10-10m
1 m = 10-6 ml = 104
1 light-year = 9.461 x 1015
Area
1 m2 = 104 cm2 = 10.76 ft2
1 ft2 = 0.0929 m2 = 144 in.2
1 in.2 = 6.452 cm2
Volume
1 m3 = 106 cm3 = 6.102 x 104 in.3
1 ft3 = 1728 in.3 = 2.83 x 10-2 m3
1 liter = 1000 cm3 = 1.0576 qt = 0.0353 ft3
1 ft3 = 7.481 gal = 28.32 liters = 2.832 x 10-2 m3
1 gal = 3.786 liters = 281 in.3
Mass
1000 kg = 1 t(metric ton)
1 slug = 14.59 kg
1 u = 1.66 x 10-27 kg
Force
1 N = 105 dyne = 0.2248 Ib
1 Ib = 4.448 N
1 dyne = 10-5N = 2.248 x 10-6 Ib
Velocity
1 mi/h = 1.47 ft/s = 0.447 m/s = 1.61 km/h
1 m/s = 100 cm/s = 3.28 ft/s
1 mi/min = 60 mi/h = 88 ft/s
Acceleration
1 m/s2 = 3.28 ft/s2 = 100 cm/s2
1 ft/s2 = 0.3048 m/s2 = 30.48 cm/s2
Pressure
1 bar = 105 N/m2 = 14.50 Ib/in.2
1 atm = 760 mm Hg = 76.0 cm Hg
1 atm = 14.7 Ib/in.2 = 1.013 x 105 N/m2
1 Pa = 1 N/m2 = 1.45 x 10-4 Ib/in.2
Time
1 year = 365 days = 3.16 x 107s
1 dy = 24 h = 1.44 x 103 min = 8.64 x 104 s
Energy
1 J = 0.738 ft.Ib = 107 ergs
1 cal = 4.186 J
1 Btu = 252 cal = 1.054 x 103 J
1 eV = 1.6 x 10-19 J
931.5 MeV is equivalent to 1 u
1 kWh = 3.60 x 106 J
Power
1 hp = 550 ft. Ib/s = 0.746 kW
1 W = 1 J/s = 0.738 ft.Ib/s
1 Btu/h 0.293 W
Physical Quantities:-
All the quantities by means of which we describe the laws of Nature and which can be measured are called physical quantities.
They are classified in to two parts:-
(a.) Fundamental Physical Quantity:- It is an elementary physical Quantity, which doesnot require any other physical quantity to express it. It is also known as basic physical quantity. They are length, mass , time, temperature, Electric current, Luminous intensity and amount of substance.
(b.) Derived physical quantity:
All those physical quantities, which can be derived from the combination of two or more fundamental quantities or derived quantities. example velocity, density, force , energy etc.
UNITS:
To measure a physical Quantity we require a standard of that physical quantity. This standard is called unit of that physical Quantity.
Dumb Question: Are units absolute things?
Ans:- Units are comperative when we mention any measurement, we actually give the comparitivity value of the quantity with respect to same internayionally fixed standard.
Fundamental Units:- The units of fundamental physical quantities are called fundamental units: | S. No. | Fundamental Physical Qty. | Units | Symbol | 1.
2.
3.
4.
5.
6.
7. | Length
Mass
Time
Electric Current
Luminous Intensity
Temperature
Amount of Substance | metre
kilogram
second
ampere
canadela
kelvin
mole | m
Kg
s
A
Cd
K
mol |
|
E-Store
