Free Measurements MCQs with Answers

41. The unit of temperature in base unit is:

• A. Celsius
• B. Degree
• C. Kelvin
• D. Fahrenheit

Explanation: Kelvin: Kelvin (K) is the base unit of temperature in the International System of Units (SI). It is an absolute temperature scale where 0 Kelvin represents absolute zero, the theoretical lowest possible temperature where all molecular motion ceases. Kelvin is commonly used in scientific and technical applications, particularly in physics and chemistry.

42. Electric charge on an object is measured as 5 micro-coulombs. The value of this charge can be expressed in terms of base units as:

• A. 5000 ampere second
• B. 5 x 10^-6 ampere second
• C. 5 x 10^6 coulomb second
• D. 500 coulomb second

Explanation: The following is the solution:Electric charge is a derived quantity, and its base unit is the coulomb (C), which is defined as the charge carried by a current of one ampere (A) in one second (s).So, 1 C = 1 A s.The prefix "micro" (μ) represents a factor of 10-6. Therefore, 5 microcoulombs (5 μC) can be expressed as:5 μC = 5 x 10-6 CTo express this value in terms of base units, we need to substitute the base unit of charge (coulomb) into the equation:5 x 10-6 C = (5 x 10-6 A) x 1 sSo, the value of 5 microcoulombs can be expressed in terms of base units as 5 x 10-6 ampere second, which is option B.

43. When the dimensions of both sides of an equation are equal, then the equation is said to be:

• A. Simultaneous
• B. Homogeneous
• C. Instantaneous
• D. Quadratic

Explanation: A dimension equation is said to be homogeneous, only and only if dimensions of equations are same on both sides.

44. Which set of the prefixes gives values in increasing order?

• A. Pico, Mega, Kilo, Tera
• B. Pico, Micro, Mega, Giga
• C. Tera, Pico, Micro, Kilo
• D. Giga, Kilo, Milli, Nano

Explanation: Pico, Micro, Mega, Giga are the prefixes in increasing order as highlighted below:

45. Name the quantity which can be measured by using the base unit kgm2s-3:

• A. Weight
• B. Pressure
• C. Power
• D. Work

Explanation: The following is the solution:As we know that:Power = Work / timeAnd,Work = force × distance F = maSo putting all that together:P = m × a × d / tSubstituting with their units that would make:P = kgm²s-3

46. Which of the following is a supplementary physical quantity?

• A. Radian
• B. Steradian
• C. Both Radian & Steradian
• D. None of the given options

Explanation: Supplementary quantities are quantities of a circle and a sphere. Supplementary units are those that aren't yet graded as either base or derive. Plane angle and solid angle are two supplementary units of two purely" geometrical physical quantities. and their units are radian (rad) and steradian (Sr) respectively.

47. A quantity 𝑥 is to be determined from the equation, 𝑥 = 𝑃 - 𝑄. 𝑃 is measured as (1.27 ± 0.02) 𝑚 and 𝑄 is measured as (0.83 ± 0.01) 𝑚. What is the percentage uncertainty in 𝑥 to one significant figure?

• A. 0.4%
• B. 2%
• C. 3%
• D. 7%

Explanation: The following is the solution:•The first figures are to be subtracted:1.27-0.83=0.44•The second figures (least counts) are to be added:0.02+0.01=0.03•Now the results from both steps are divided:=(0.03/0.44)x100=6.82% ≈ 7%Hence, option D is correct.

48. The dimensional formula for change in momentum is same as that for:

• A. Force
• B. Impulse
• C. Acceleration
• D. Velocity

Explanation: The following is the solution:Impulse can be defined as "The sudden force acting on an object for a short interval of time".It is equal to ∆PThe units of both momentum and impulse are the same so their dimensional formulas are also same.

49. Which one of the following physical quantity does not the dimension of force per unit area:

• A. Stress
• B. Strain
• C. Young modulus
• D. Pressure

Explanation: The strain unit is dimensionless. It is the ratio between the length shift and the initial length, so it is unit-less. Thus B, strain, is the correct option

50. A value for the acceleration of free fall on Earth is given as (10+-2) m s-2. Which statement is correct?

• A. The value is accurate but not precise
• B. The value is both accurate and precise.
• C. The value is neither precise nor accurate.
• D. The value is precise but not accurate.

Explanation: The 'true' value of the acceleration of free fall is 9.81 m s-2.From the value given in the question, the acceleration of free fall can be from (10 -2 =) 8 ms-2 to (10 + 2 =) 12 ms-2.The true value (= 9.81 ms-2) lies within the range given by the uncertainty, and therefore the stated value is accurate. Precision deals with how small or large the uncertainty is. A precise set of measurements would have a small scatter of readings. Here, the value is not precise as the uncertainty is large