Question

1. (a) State any three characteristic of physicist. marks) (b) Explain the merits of using SI units for measurement marks) (c) State the three fundamental mechanical quantities marks) (d) Copy and complete the Physical Quantity table below. marks) Physical quantity Units Symbol Amount of substance Mol Electric current Length M Mass kg Time Second kelvin K Luminous intensity Candela A (& 2. (a) Tabulate four differences between Mass and weight. (b) State four reliable instrument for measuring the temperature of a body (c) State three reasons why water is NOT used as a thermometric liquid? (d)State two reasons why alcohol is used as thermometric liquid? ( C 3. (a) State three advantages of mercury as a thermometric liquid. (b) Change 65°F to centigrade (c) Explain the concept work" to your science colleague. (d) State the principle of Conservation Of Energy (e) State Isaac Newton First law of motion. 7 =

Answer 1

Answer

Q1

a) The physicist should have

1) Have strong scientific temper

2) Have a methodical, analytical approach to work.

3) Be able to think clearly and logically.

b)

The first advantage is that its value is understood by physicist world-wide,since it is based on seven fundamental units (meter for length, kilogram for mass, second for time, ampere for electric current, kelvin for absolute temperature, mole for amount of substance in chemistry, and candela for luminous intensity). So international projects can easily be carried out.

The second advantage is that its multiples and sub-multiples are consistent and are powers of 10 - unlike the relationship between say inches, feet, yards, chains, furlongs and miles where the relationships are 12, 3, 22, 10 and 8.

The third advantage is that when it is used in engineering calculations to calculate some other SI quantity, the constant used is usually 1 - for example one watt is the power needed to move one kilogram as a velocity of one metre per second against a force of one newton, whereas one horsepower is the power needed to moved 550 pounds at a speed of one foot per second against gravity. (This is called coherence of units).

c) The three fundamental mechanical quantities are MASS, LENGTH and TIME

d)

PHYSICAL QUANTITY	UNITS	SYMBOL
Amount of substance	mole	mol
Electric current	ampere	A
Length	metre	m
Mass	kilogram	kg
Time	second	s
Temperature	kelvin	K
Luminous intensity	candela	cd

NB : As per HOMEWORKLIB RULES only one question and a maximum of four subparts is allowed to answer.