Tag: measuring mass

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Questions Related to measuring mass

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

Spring of spring balance must be _______ in nature.

  1. Elastic

  2. Non-elastic

  3. Rubber

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

The working principle of spring balance is :

  1. Newton's laws of motion

  2. Hooke's law

  3. Ohm's law

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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  $F = -kx$.

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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.
Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

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:

  1. 15 kg

  2. 22 kg

  3. 50 kg

  4. 0.5 kg
Reveal answer Fill a bubble to check yourself
B Correct answer
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$

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

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

  1. 22.5 kg

  2. 2.25 kg

  3. 1.15 kg

  4. 11.5 kg
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A spring balance measures the total weight of the system. Adding an ice cube increases the total weight by the weight of the ice cube (1.5 kg). Thus, 10 kg + 1.5 kg = 11.5 kg.

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

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?

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
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.