Tag: motion and measurement

Quizzes (11) Questions (114)

Questions Related to motion and measurement

Multiple choice physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

What is number of significant figures in $0.310\times 103$ ?

  1. 2

  2. 3

  3. 4

  4. 6
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since the numbers $0.310$ and $103$ have 3 significant figures each. In the case of the multiplication, the maximum number of significant figures is the same as that of the number of significant figures in decimal number., so the final answer must also have 3 significant figures.

Multiple choice physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

Which of the following pairs of physical quantities have same dimensions?

  1. Force and power

  2. Torque and energy

  3. Torque and power

  4. Force and torque
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Torque is the moment of force given by:$ \vec\tau=\vec r\times \vec F$

It’s unit is Newton-meter.

The unit of work/energy is also Newton-meter or Joule.

Thus, both of these physical quantities have the same units/dimensions.

$[Torque]=[M][L]^{2}[T]^{−2}=[Energy]$
Multiple choice physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

Which of the following statements is incorrect regarding mass. ?

  1. It is a basic property of matter.

  2. The SI unit of mass is kg.

  3. The mass of an atom is expressed in u.

  4. It depends upon the temperature, pressure or location of the object in space.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass is property of mater, which is independent of other properties like temperature, pressure or location of the object in space.

Multiple choice physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

Which of the following is unitless quantity?

  1. Pressure gradient

  2. Displacement gradient

  3. Force gradient

  4. Velocity gradient
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The gradient of any physical quantity is computed to as per unit length. This means it is a rate with respect to length. So, the Displacement gradient will also be length per unit length. Because a displacement gradient is the ratio of two quantities having dimensions of "length". That is, a displacement gradient has units of a meter per meter for example. 

The length dimensions will be cancelled, and we have a unitless quantity. While others will be having certain units. Hence it is a unitless quantity.

Thus option B is correct.