UNITS AND MEASUREMENTS-QUIZ 18

UNITS AND MEASUREMENTS-QUIZ 18

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. Pressure gradient has the same dimension as that of

•  Velocity gradient
•  Potential gradient
•  Energy gradient
•  None of these

Solution
(d) Velocity gradient =v/x=([LT^-1])/([L])=[T^-1]
Potential gradient =V/x=[ML² T^-3 A^-1 ]/[L] =[MLT^-3 A^-1 ]
Energy gradient =E/x=([ML² T²])/([L])=[MLT^-2]
And pressure gradient =P/x=([ML^-1 T^-2])/([L])=[ML^-2 T^-2]

Q2.The damping force on an oscillator is directly proportional to the velocity. The units of the constant of proportionality are

•  kgms^-1
•  kgms^-2
•   kgs^-1
•  kgs

Solution
(c) F∝v⇒F=kv k=F/v⇒[k]=([kgms^-2])/([ms^-1])=kg s^-1

Q3. Dimensional formula of capacitance (or farad) is

•   M^-1 L^-2 T⁴ A²
•  ML² T⁴ A^-2
•  MLT^-4 A²
•  M^-1 L^-2 T^-4 A^-2

Solution
(a) [C]= (Q/V)=((Q²/W ))=[((A² T²)/(ML² T^-2 ) )]=[M^-1 L^-2 T⁴ A²]

Q4. Joule-second is the unit of

•  Work
•  Momentum
•  Pressure
•  Angular momentum

Solution
(d) τ=dL/dt ⇒dL= τ ×dt=r×F×dt
i.e., the unit of angular momentum is joule-second

Q5.If L=2.331 cm,B=2.1 cm,then L+B is equal to

•  4.431 cm
•  4.43 cm
•  4.4 cm
•  4 cm

Solution
(b) In mathematical operation, involving addition the result would be correct up to minimum number of decimal places in any of the quantity involve.
Given, L=2.3331 cm and B=2.10 cm. Taking correct up to decimal places and since, can be rounded off less than 5, the preceding digit is unaffiliated.
∴L=2.33 cm,B=2.10 cm
L+B=2.33+2.10=4.43 cm  

Q6. If the radius of the sphere is (5.3±0.1)cm. Then percentage error in its volume will be

•  3+6.01×100/5.3
•  1/3×0.01×100/5.3
• (((3×0.01)/5.3 ))×100
•  0.1/5.3×100

Solution
(c) Volume of sphere (V)=4/3 πr³ % error in volume =3×∆r/r×100=(3×0.1/5.3)×100

Q7.The dimension of magnetic field in M, L, T and C (coulomb) is given as

•  MT² C^-2
•  MT^-1 C^-1
•  MT^-1 C^-1
•  MLT^-1 C^-1

Solution
(b) [B]=([F])/([I][L])=([MLT^-2])/([CT^-1 ][L])=[MT^-1 C^-1]

Q8.In a system of units if force (F), acceleration (A), and time (T) are taken as fundamental units then the dimensional formula of energy is

•  FA² T
•  FAT²
•  F² AT
•  FAT

Solution
(b) E=KF^a A^b T^c
[ML² T^-2 ]=[MLT^-2 ]^a [LT^-2 ]^b [T]^c
[ML² T^-2 ]=[M^a L^(a+b) T^-2a-2b+c]
∴a=1,a+b=2 ⇒b=1 And -2a-2b+c=-2⇒c=2
∴E=KFAT²

Q9.In the equation S_nth the =u+a/2 (2n-1), the letters have their usual meanings. The dimensional formula of S_nth is

•  [ML⁰ T]
•  [ML^-1 T^-1]
•  [M⁰ LT^-1]
•  [M⁰ LT⁰]

Solution
(c) S_nth represents the distance covered in nth sec.

Q10. Which of the following system of units is not based on units of mass, length and time alone

•  SI
•  MKS
•  FPS
•  CGS

Solution
(a) Because in S.I. system there are seven fundamental quantities