CHAPTER 1 MEASUREMENTS

 

1.1      Choose the best option.

1.      The main contribution of modern physics
(a) Newton’s laws of motion	(b) Thermodynamics laws
(c) Kinetic theory	(d) Special theory of relativity
2.      The branch of physics which deals with the properties and interaction nuclear particles (protons and neutrons) is called
(a) Molecular physics	(b) Plasma physics
(c) Nuclear physics	(d) Solid State Physics
3.      The fundamental physical quantities which form the basis of the SI units are
(a) Force weight and time	(b) Mass, length, and time
(c) Mass, length, and force	(d) Mass, energy, and time
4.      Which one of the following is base physical quantity?
(a) Pressure	(b) Temperature
(c) Density	(d) Energy
5.      Which list of units contains three base quantities and two derived quantities?
(a) Kelvin, newton, second, kilogram, ohm	(b) Volt, joule, ampere, coulomb, meter
(c) Kilogram, meter, second, mole, kelvin	(d) Mole, hertz, kelvin, joule, newton
6.      Light year is the unit of
(a) Time	(b) Distance
(c) Speed	(d) Velocity
7.      µm x mm is equal to
(a) 109 m	(b) 10-9 m
(c) 109 m2	(d) 10-9 m2
8.      The derived unit joule in terms of base units is
(a) kgms-2	(b) kgm2s-2
(c) kgm-1s-2	(d) kgm-2s-2
9.      The scientific notation of a measured value 0.0092 m
(a) 9.2 x 103 m	(b) 9.2 x 10-3 m
(c) 9.2 x 105 m	(d) 9.2 x 10-5 m
10.  By using vernier callipers a length is measured by four students. Which one of the following is correct.
(a) 4.5 cm	(b) 4.51 cm
(c) 4.510 cm	(d) 4.5100 cm
11.  What is the absolute precision of the referred result 8.52 cm?
(a) 1 cm	(b) 0.1 cm
(c) 0.01 cm	(d) 0.001 cm
12.  The number of significant figures of the value 0.0202 is
(a) Two	(b) three
(c) four	(d) five
13.  Which one of the following measurements is the most significant?
(a) 203000	(b) 203x103
(c) 20.3x104	(d) 2.03x 105

14.  The length the length of a body is measured as 3.51 m, if the accuracy is 0.01 m, then the Percentage uncertainty in the measurements is
(a) 3.51 %	(b) 0.035 %
(c) 0.28 %	(d) 28.65 %
15.  The dimension of moment of inertia is
(a) [MLT°]	(b) [ML2T°]
(c) [ML-2T°]	(d) [M2LT°]
16.  Which pair of physical quantities has same dimension
(a) Velocity and acceleration	(b) Mass and weight
(c) Inertia and moment of inertia	(d) Work and potential energy

 

Answers

1. (d) Special theory of relativity
2. (c) Nuclear physics
3. (b) Mass, length, and time
4. (b) Temperature
5. (a) Kelvin, newton, second, kilogram, ohm
6. (b) Distance
7. (b) 10^-9 m
8. (b) kgm2s^-2
9. (b) 9.2 x 10^-3 m
10. (b) 4.51 cm
11. (c) 0.01 cm
12. (b) three
13. (a) 203000
14. (c) 0.28 %
15. (b) [ML²T°]
16. (d) Work and potential energy

1.2      Short question

3. Convert a year into months, days, hours, minutes, and seconds.

ans.                        

One year =	12 months
One year =	365 days
One year =	8760 hours
One year =	525600 minutes
One year =	31536000 seconds

7. How can you derive the unit of watt in term of base unit?

ans.                        Watt is the unit of power, and it is defined a

19. According to Hook’s law the restoring force F, due to a body attach to a spring is given by F=-kx. Calculate the dimension of the spring constant k.

an    ans. 

1.3     Numerical problems

2. Mass of neutron is 1.67 x 10^-27 kg. Calculate the number of neutrons in a piece of metal whose net mass is one gram.

Solution:

6.      The radius of a rod is 0.24 cm. Find its cross-sectional area with appropriate significant figures.

10.      The centripetal force ‘F’ acting on a particle (moving uniformly in a circle) depends on the mass ‘m’ of the particle, its velocity ‘v’ and radius ‘r of the circle. Derive dimensionally formula for force ‘F’