Q.1
Which one of the following lists contains only SI base units?
A kelvin, metre, mole, ampere, kilogram
C kilogram, newton, metre, ampere, ohm C
Answer: A
The base quantities (and their units) are: mass (kilogram), length (metre), time (second), current (ampere), temperature (kelvin) and amount of substance (mole).
Q.2
Which one of the following pairs comrises two SI base units?
A ampere, degree celsius
C coulomb, degree celsius
Answer: B
SI base units are metre, kilogram, second, ampere, kelvin and mole.
Q.3
In term of the base units of mass, length and time, the kg, m and s, what are the base units of work, the joul (J)?
A kg m-1 s2
Answer: B
Work = force x distance
Joule = base units of force x base units of distance
= kg m s-2 x m = kg m s-2
Q.4
Which pair does not contain any SI base units?
A ampere, mole B coulomb, metre C newton, ohm D second, volt
Answer: C
SI base units are metre, kilogram, second, ampere, , kelvin and mole.
Q.5
What are the SI base units of specific heat capacity?
A m s-2 K-1
Answer: C
From eq. Q = mc∆T
Then base units of c = base units of Q/(base units of m x base units of ∆T)
= (kg m2 s-2)/[(kg) x (K)] = m2 s-2 K-1
Q.6
Which one of the following expressions has different units from the other three?
A density x volume x velocity B
C the Young modulus x area D
Answer: A
Base units of density x volume x velocity
= (kg m-3) x (m3) x (m s-1) = kg m s-1
Base units of rate of change of momentum, the Young modulus x area, and weight are kg m s-2.
Q.7
What are the SI base units of pressure?
A kg m s-1 B
Answer: B
Pressure = force/area
Base units of pressure = base units of force/base units of area
= (kg m s-2)/(m2) = kg m-1 s-2
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