Have you seen your grandmom measuring the size of a cloth using her palm span? She measures the size of the cloth for accuracy in her stitching. Size and quantity are very common terms that have been associated with human civilization since time immemorial. In this chapter, we shall throw light on how to differentiate between sizes and quantities?
Size and Quantity
Have you ever been to shopping with your mother? In the course of shopping, what do you notice? Everything you buy is measured. Be it vegetables or any dress material every shopkeeper practices a different mode of measurement. For finding the length, a shopkeeper at the cloth store uses a meter tape, while the vegetable vendor uses the weighing balance for measuring the quantity of the vegetables.
But how do you measure the size of an object? Well, the answer is simple, by comparing. By comparison of two objects, you come to know which object is bigger. For example a whale shark. How do you know that it is the biggest animal on Earth? You know this because you haven’t come across any bigger animal.
Now how do you say a fish is smaller than a shark? You say that because when you compare the two the size of one is greater than the other. Here did you know that the smallest fish is as small as 1cm while the largest one is as big as 18 meters. So when you put them together you know the difference between the sizes.
Next comes the weight of an object. When we are measuring the quantity of any object we intend to measure its weight. Generally weighing a quantity of any substance need a weighing scale for accuracy, but that is not accessible every time. Now how do you say an object is heavier or has more weight.
The first thing you look while knowing the quantity of an object is its size. Generally, the bigger the size the heavier is the object. Let’s take the same example of fish and whale. A fish of size 1 cm weighs in some milligrams while a whale shark measures 16000 kg. Immense isn’t it?
The size also determines the weight or quantity of an object. Generally, an object bigger in size is heavier than its other smaller counterpart. But this may not always be true. to understand this, first, guess the following:
From a bag filled with 1kg cotton and 1 kg sugar, which is heavier? The first answer which comes to your mind is the cotton because it occupies a bigger bag! This means that the size of an object alone is not the judging factor for quantity, it is an essential factor that characterizes the heavy weight of the object.
Quantity of More than One Object
When we need to calculate the quantity of an object, we weigh. The quantity is written with Kilogram(kg), Gram (g) and Milligram (mg) as units. When we have to measure the quantity of more than one same weighing objects we follow the system shown here: If 1 fish would weigh 15 kg, then 7 such fishes shall weigh 7 multiplied with 15kg. So here the weight of all the fishes shall be 105 kg.
For example, if you need to buy 10 kg of dried fish and 5 kg of fresh fish from the fish market and if 1kf of fresh fish costs Rs 20 and dried fish costs Rs.70, how much do you need to pay?
Solution: 1 kg of Fresh fish costs: Rs. 20
5 kg shall cost: 5 × 20 = Rs. 100
1 kg of dried fish costs= Rs 70
10 kg shall cost =10 × 70 = Rs 700
Total money needed = 700 + 100 = Rs. 800
In the above example, we have multiplied the quantity of one object with the number of such objects. This is how bills and total expenditures are calculated. Now let’s see how do we calculate the profit or loss in an object.
While calculating the loss or profit of an object, we first calculate the total cost incurred on it in repairs, handling and travelling. Then subtract the costs from selling price.
A dried fish is sold at Rs 70 per 1 kg. The 1kg fish needs 1 kg salt of Rs 5 for drying while travelling cost amounts to Rs 500. How much do we earn when we sell 60 kg fish.
The selling price of fish = Rs 70 per kg
The selling price of 60 kg fish= 60 ×70 = Rs 4200
Salt needed to dry 1 kg fish = 1kg
cost of 1 kg salt = Rs 5
cost of 60 kg fish = 5 ×60 = Rs 300
Travelling charges = Rs 500
Total cost incurred = 500+300 = 800
Profit made = 4200 -800 = Rs 3400
Therefore profit earned = Rs 3400
Measuring size and quantity finds use in various calculations of area, volume and money. In your higher classes, you shall learn about calculations related to these concepts. What we learned here is just the basics, which will be useful to your higher standards.
Solved Example for You
Question: State whether the Following statement is True or False: Weight is the name of the force exerted on an object due to the acceleration of gravity.
Solution: Option A. True. Weight=mg where m=mass of object, g=gravity and mg=force exerted on an object due to the acceleration of gravity.