Tag: measurement of mass

Questions Related to measurement of mass

Spring of spring balance must be _______ in nature.

physics measurements and units measuring mass measurement of mass measuring instruments

  1. Elastic

  2. Non-elastic

  3. Rubber

  4. None of these

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Correct Option: A
Explanation:

Spring balance is used to measure the weight of the object. The working principle of spring balance is Hooke's law. Since Hooke's law is valid only for elastic objects, thus spring used in the spring balance must be elastic in nature.

Weight is a______

physics measurements and units measuring mass measurement of mass measuring instruments

  1. Scalar quantity

  2. Vector quantity

  3. Both

  4. None

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Correct Option: B
Explanation:

Weight is a vector quantity. Weight of the object refers to the force with which the object is attracted towards the earth.

The working principle of spring balance is :

physics measurements and units measuring mass measurement of mass measuring instruments

  1. Newton's laws of motion

  2. Hooke's law

  3. Ohm's law

  4. None of the above

Show answer
Correct Option: B
Explanation:

Spring balance is used to measure the weight of the object. When a load is hung on the spring, it stretches and the spring's extension is proportional to the weight of the object. The working principle of the spring balance is Hooke's law  which is  $F = -kx$.

State whether given statement is True or False.
Weight of same object differs at different distances from the equator. 

physics measurements and units measuring mass measurement of mass measuring instruments

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
We know that acceleration due to gravity differs at different distances from the equator but the mass of the object remains constant.
Weight of the object   $W = mg$
Thus weight of the object differs at different distances from the equator.

The weight of an object :

physics measurements and units measuring mass measurement of mass measuring instruments

  1. refers to the force with which it is attracted towards the earth

  2. refers to its inertia

  3. is the same as its mass but having different units

  4. none of these

Show answer
Correct Option: A
Explanation:
Weight of the object  $W = mg$
Weight of the object refers to the force with which it is attracted towards the earth.

The SI unit of weight is :

physics measurements and units measuring mass measurement of mass measuring instruments

  1. Kg

  2. Newton

  3. Pounds

  4. Tonne

Show answer
Correct Option: B
Explanation:

Weight of the substance is given by  $W = mg$
where $m$ is the mass of substance and $g$ is the acceleration due to gravity.
SI unit of weight is Newton represented by $N$.

State whether given statement is True or False.
Weight remains constant at all places.

physics measurements and units measuring mass measurement of mass measuring instruments

  1. True

  2. False

Show answer
Correct Option: B
Explanation:
Weight of the object  $W = mg$
We know that acceleration due to gravity $g$ differs at different distances from the equator but mass of the object remains constant. Thus, weight of the object varies at different places.
Thus the given statement is false.

A spring balance has a scale reading from 0 to 50 kg. The length of the scale is 20 cm. A body suspended to the spring balance when displaced and released oscillates with a period of $0.6$ second. The mass off the body is:

physics measurements and units measuring mass measurement of mass measuring instruments

  1. 15 kg

  2. 22 kg

  3. 50 kg

  4. 0.5 kg

Show answer
Correct Option: B
Explanation:

According to the question,

The maximum mass scale can read $M=50\,kg$
The maximum displcement of spring $=$ 
length of scale, $l=20\,cm\,=0.2\,m$
$T$ (time period) $=0.6\,s$
Maximum force exerted on the spring $F=mg$
So,
$g=$acceleration due to gravity $ = 9.8\,m/{s^2}$
$F = 50 \times 9.8 = 490$
Since, speing constant,
$k = \frac{F}{l}$
$ = \frac{{490}}{{0.2}}$
$ = 2450\,N\,{m^{ - 1}}$
$m$ is suspended from the balance 
$T = 2\pi \sqrt {\frac{m}{k}} $
Since,
$m = {\left( {\frac{T}{{2\pi }}} \right)^2} \times k$
$ = {\left( {\frac{{0.6}}{{2 \times 3.14}}} \right)^2} \times 2450$
$ \approx 22\,kg$

A spring balance reads $10kg$ when a bucket of water is suspended from it. What is the reading on the spring balance when an ice cube of mass $1.5kg$ is into the bucket

physics measurements and units measuring mass measurement of mass measuring instruments

  1. 22.5 kg

  2. 2.25 kg

  3. 1.15 kg

  4. 11.5 kg

Show answer
Correct Option: D

A child stands on a bathroom scale while riding in an elevator. The child's weight when the elevator is not moving is 100 Ibs. What does the scale read when the elevator accelerates upward while travelling downward?

physics measurements and units measuring mass measurement of mass measuring instruments

  1. greater than 100 Ibs

  2. less than 100 Ibs

  3. exactly 100 Ibs

  4. The same as it reads when accelerating downward while travelling upward, by symmetry.

Show answer
Correct Option: A
Explanation:

Given,

When lift is not moving, gravity force act downward, weighing machine show $\vec{F}=m\vec{g}=100\,lbs\,$force.

When lift start moving upward with acceleration$\vec{a}$, Normal reaction force on child increase by $m\vec{a}$

Therefore, net weight on weighing machine become, $\vec{F}=m\vec{g}+m\vec{a}$

Hence, scale will show weigh greater than $100\,lbs$force.