Question

A jeweller kept a diamond of mass $5.42gm$ inside a box of mass $1.2kg$. Find the combined mass of diamond and box up to appropriate significant figures.

Answer 1

Hint: In this particular question, we will convert the mass of a diamond that is $5.42gm$ in kilograms. As we are asked to calculate the unit of mass and S.I. the unit of mass is kilogram.

Complete step-by-step answer:
Mass is defined as the matter that is present in the given object. It can be both a property of a physical body and a measure of a resistance to acceleration with some amount of force is applied. Following are the units that are most commonly used for the measurement of mass:

(i)Gram
(ii)Kilogram

S.I. the unit of mass is kilogram.

Let the weight of box $= x$
That is $x = 1.2kg$
Let the weight of diamond $= y$
That is $y = 5.42gm$

As, we have to calculate the mass of a diamond, therefore we will convert grams into kilogram

That is, $\dfrac{{5.42}}{{1000}} = 0.00542kg$ (1 gram $= 0.001kg$)
Now, the sum of $x$ and $y$ will be

$x + y = 1.2 + 0.00542$
$= 1.20542kg$

Hence, out of all weight measurements, the weight of the box will be $1.2kg$ and has the least number of decimal places that is one.

Therefore, rounding off the above result to the first decimal place, we have the total weight of the box $x + y = 1.2kg$

Note – Whenever we come up with this type of question, where we are asked to find the mass of a quantity then it should be noted that mass is different from weight even though the terms are sometimes used interchangeably. Also, one must know the S.I. unit of mass, by using these basics one can easily solve numerical problems related to mass.