UNITS AND MEASUREMENTS-QUIZ 17

UNITS AND MEASUREMENTS-QUIZ 17

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. Position of body with acceleration ‘a’ is given by x=Ka^m tⁿ, here t is time. Find dimensions of m and n

•  m=1,n=1
•  m=1,n=2
•  m=2,n=1
•  m=2,n=2

Solution
(b) As x=ka^m×tⁿ
[M⁰LT⁰ ]=[LT^-2 ]^m [T]ⁿ=[L^m T^(-2m+n)] ∴m=1 and -2m+n=0 ⇒n=2

Q2.A pressure of 10⁶ dyne cm^-2 is equivalent to

•  10⁵ N m^-2
•  10⁴ N m^-2
•   10⁶ N m^-2
•  10⁷ N m^-2

Solution
(a) 1 Newton = 10⁵ dyne and 1m=100 cm

Q3. The unit of Planck’s constant is

•   Joule
•  Joule/s
•  Joule/m
•  Joule-s

Solution
(d)Joule-s

Q4. Candela is the unit of

•  Electric intensity
•   Luminous intensity
•  Sound intensity
•  None of these

Solution
(b)Luminous intensity

Q5.The dimensions of gravitational constant G and the moment of inertia are respectively

•  ML³ T^-2;ML² T⁰
•  M^-1 L³ T^-2;ML² T⁰
•  M^-1 L³ T^-2;M^-1 L²T
•  ML³ T^-2;M^-1 L² T

Solution
(b)M^-1 L³ T^-2;ML² T⁰  

Q6. What will be the unit of time in that system in which the unit of length is metre, unit of mass is kg and unit of force is kg wt?

•  (9.8)²sec
•  9.8 sec
• √9.8 sec
•  1/√9.8 sec

Solution
(d) We know [F]=[MLT^-2]
T²=ML/F=(1kg×1m)/(1kg-wt)=(1kg×1m)/9.8N T=1/√9.8 sec

Q7.If pressure P, velocity V and time T are taken as fundamental physical quantities, the dimensional formula of force is

•  PV² T²
•  P^-1 V² T^-2
•  PVT²
•  P^-1 VT²

Solution
(a) Let F ∝P^x V^y T^z By substituting the following dimensions: [P]=[ML^-1T^-2 ][V]=[LT^-1 ],[T]=[T] and comparing the dimension of both sides x=1,y=2,z=2, so F=PV² T²

Q8.If I is the moment of inertia and ω the angular velocity, what is the dimensional formula of rotational kinetic energy 1/2 Iω²?

•  [ML² T^-1]
•  [M²L^-1 T^-2]
•  [ML² T^-2]
•  [M² L^-1 T^-2]

Solution
(c) Do not think in terms of I and ω. Remember; kinetic energy is fundamentally ‘work’ W=Force × distance =[MLT^-2 ]×[L] =[ML² T^-2]

Q9.The dimensional formula for Planck’s constant (h) is

•  ML^-2 T^-3
•  ML² T^-2
•  ML² T^-1
•  ML^-2 T^-2

Solution
(c) E=hv⇒[ML² T^-2 ]=[h][T^-1]⇒[h]=[ML² T^-1]

Q10. The physical quantities not having same dimensions are

•  Speed and (μ₀ ε₀ )^(-1/2)
•  Torque and work
•  Momentum and Planck’s constant
•  Stress and Young’s modulus

Solution
(c) Momentum [MLT^-1], Plank’s constant [ML² T^-1]