NCERT Solutions for Class 11-science Physics Chapter 2 - Units and Measurements

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Chapter 2 - Units and Measurements Exercise 35

Solution 1

(a) 1 cm =Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Volume of the cube = 1 cm3

But, 1 cm3 = 1 cm Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 1 cm Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 1 cm = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

 



Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements1 cm3 = 10-6 m3

Hence, the volume of a cube of side 1 cm is equal to 10-6 m3.

(b) The total surface area of a cylinder of radius r and height h is

S = 2 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurementsr (r + h).

Given that,

r = 2 cm = 2 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 1 cm = 2 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 10 mm = 20 mm

h = 10 cm = 10 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 10 mm = 100 mm

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
= 15072 = 1.5 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 104 mm2

(c) Using the conversion,

1 km/h = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

 

Therefore, distance can be obtained using the relation:

Distance = Speed Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements Time = 5 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 1 = 5 m

Hence, the vehicle covers 5 m in 1 s.

(d) Relative density of a substance is given by the relation,

Relative density = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Density of water = 1 g/cm3

 

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Again, 1g =Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements kg

1 cm3 = 10-6 m3

1 g/cm3 = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements11.3 g/cm3 = 11.3 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 103 kg/m3

Solution 2
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 3
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 4
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 5

The given statement is true because a dimensionless quantity may be large or small in comparison to some standard reference. For example, the coefficient of friction is dimensionless. The coefficient of sliding friction is greater than the coefficient of rolling friction, but less than static friction.

(a) An atom is a very small object in comparison to a soccer ball.

(b) A jet plane moves with a speed greater than that of a bicycle.

(c) Mass of Jupiter is very large as compared to the mass of a cricket ball.

(d) The air inside this room contains a large number of molecules as compared to that present in a geometry box.

(e) A proton is more massive than an electron.

 (f) Speed of sound is less than the speed of light.

Solution 6
Distance between the Sun and the Earth:


= Speed of light Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements Time taken by light to cover the distance

Given that in the new unit, speed of light = 1 unit

Time taken, t = 8 min 20 s = 500 s

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And MeasurementsDistance between the Sun and the Earth = 1 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 500 = 500 units

Solution 7
A device with minimum count is the most suitable to measure length.

(a) Least count of vernier callipers

= 1 standard division (SD) - 1 vernier division (VD)

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

(b) Least count of screw gauge = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements



(c) Least count of an optical device = Wavelength of light Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 10-5 cm

= 0.00001 cm

Hence, it can be inferred that an optical instrument is the most suitable device to measure length.
Solution 8

Magnification of the microscope = 100

Average width of the hair in the field of view of the microscope = 3.5 mm

Actual thickness of the hair is Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements  = 0.035 mm.


Solution 9
(a) Wrap the thread on a uniform smooth rod in such a way that the coils thus formed are very close to each other. Measure the length of the thread using a metre scale. The diameter of the thread is given by the relation,
 
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

(b) It is not possible to increase the accuracy of a screw gauge by increasing the number of divisions of the circular scale. Increasing the number divisions of the circular scale will increase its accuracy to a certain extent only.

(c) A set of 100 measurements is more reliable than a set of 5 measurements because random errors involved in the former are very less as compared to the latter.

Solution 10
Area of the house on the slide = 1.75 cm2
Area of the image of the house formed on the screen = 1.55 m2
= 1.55 Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements 104 cm2
Arial magnification, ma = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

 
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And MeasurementsLinear magnifications, ml = Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
 
 
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
 


Chapter 2 - Units and Measurements Exercise 36

Solution 1
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 2
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 3
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 4
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 5
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 6
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 7
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 8
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 9
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Chapter 2 - Units and Measurements Exercise 37

Solution 1
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 2
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 3
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 4
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 5
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 6
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 7
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 8
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 9
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 10
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Chapter 2 - Units and Measurements Exercise 38

Solution 1
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 2
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

Solution 3
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Solution 4
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements
Ncert Solutions Cbse Class 11-science Physics Chapter - Units And Measurements

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