UNITS AND MEASUREMENTS-QUIZ 16

UNITS AND MEASUREMENTS-QUIZ 16

Dear Readers,

As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background. Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced. .

Q1. The ratio of the dimension of Planck’s constant and that of moment of inertia is the dimension of

•  Frequency
•  Velocity
•  Angular momentum
•  Time

Solution
(a) h/I=[(ML² T^-1/(ML² )]=[T^-1]

Q2.The equation of a wave is given by Y = A sin⁡ω ((x/υ-k ))
where ω is the angular velocity and υ is the linear velocity. The dimension of k is

•  LT
•  T
•   T^-1
•  T²

Solution
(b) From the principle of homogenity (x/v) has dimensions of T

Q3. The dimensional formula for impulse is

•   [MLT^-1 ]
•  [ML^-1 T]
•  [M^-1 LT^-1]
•  [ML^-1 T^-1 ]

Solution
(a) Impulse=force ×time =[MLT^-2 ][T]
=[MLT^-1 ]

Q4. The radius of the sphere I (4.3±0.1)cm. The percentage error in its volume is

•  0.1/4.3×100
•   3×(0.1×100)/4.3
•  1/3×(0.1×100)/4.3
•  3+(0.1×100)/4.3

Solution
(a) Percentage error in radius is 0.1/4.3×100. again, V∝R³

Q5.Size of universe is about

•  Ten million light years
•  Million light years
•  Hundred million light years
•  10 million light years

Solution
(d) Size of universe is about 10²⁶ m=10⁶×(9.46×10¹⁵)m =10¹⁰ly  

Q6. A cube has a side of length 1.2 ×10^-2 m. Calculate its volume.

•  1.7×10^-6 m³
•  1.73×10^-6 m³
• 1.70×10^-6 m³
•  1.732×10^-6 m³

Solution
(a) Volume V=I³=(1.2×10^-2 m)³=1.728×10⁶ m³ ∵ length lhas two significance figures. Therefore, the correct answer is
V=1.7×10^-6 m³

Q7.The SI unit of momentum is

•  kg/(m )
•  (kg.m)/sec
•  (kg.m^2)/sec
•  kg×newton

Solution
(b) mv=kg((m/sec ))

Q8.A calorie is a unit of heat and equal 4.2 J. Suppose we employ a system of units in which the unit of mass is αkg,
the unit of length is β metre and the unit of time is γ sec. In this new system. 1 calorie =

•  α^-1 β^-2 γ²
•  4.2αβ² γ²
•  αβ² γ²
•  4.2α^-1 β^-2 γ²

Solution
(d) [Calorie]=[ML² T^-2] Comparing with general dimensional formula [M^a L^b T^c ], we get
a=1,b=2,c=-2. n₂=4.2[1kg/αkg]¹ [1m/βm]² [1s/γs]^-2=4.2α^-1 β^-2 γ²

Q9.Number of base SI unit is (Given that radius of earth = 6400 km)

•  4
•  7
•  3
•  5

Solution
(b)7

Q10. Dimensions of bulk modulus are

•  [M^-1 LT^-2 ]
•  [ML^-1 T^-2 ]
•  [ML^-1 T^-2 ]
•  [M² L² T^-1 ]

Solution
(b) Bulk modulus K=(normal stress)/(volumetric strain)
=(F/A)/(-∆V/V) =-FV/(A ∆V) Now, F/A=p ∴ K=pV/∆V As volumetric strain is dimensionless.
∴Dimensions of K=dimensions of normal stress
⇒ [K]=[Ml^-1 T^-2 ]