Question

Which of the following is NOT a unit of weight or mass? (A) ton (B) gram (C) kilowatt (D) ounce

Short answer

Option (C) kilowatt is not a unit of weight or mass.

Step-by-step solution

Check option (A) - ton

The ton is a unit of weight, specifically, it measures mass. Therefore, option (A) cannot be the correct answer.

Check option (B) - gram

The gram is a unit of mass. It is a basic unit in the metric system to measure weight. So, option (B) cannot be the correct answer.

Check option (C) - kilowatt

The kilowatt is a unit of power, not a unit of weight or mass. It is used to measure the rate at which energy is used or produced. Hence, option (C) is the correct answer since it is not a unit of weight or mass.

Check option (D) - ounce

The ounce is a unit of weight, which is used to measure mass in the imperial system. It is not the correct answer as it measures mass. So, the correct answer is option (C) kilowatt, as it is not a unit of weight or mass.

Key concepts

Metric System

When we talk about measuring weight and mass, one of the most commonly used systems around the world is the metric system. It is an internationally recognized system of measurement based on multiples of ten. The fundamental unit of mass in the metric system is the kilogram, which is denoted by 'kg'. While the kilogram measures larger quantities of mass, smaller masses are often measured in grams (g). In fact, there are 1,000 grams in a single kilogram. For weight measurement, the metric system also uses tonnes where 1 tonne is equivalent to 1,000 kilograms.

It's important for students to recognize that these units are part of a decimal system, which makes conversion between different scales straightforward – you simply move the decimal point. For instace, to convert kilograms to grams, you would move the decimal point three places to the right. This simplicity is one of the reasons the metric system is preferred in science and many countries worldwide.

Imperial System

On the other hand, the imperial system uses different units of measurement, which are more commonly used in the United States. When it comes to weight and mass, the imperial system uses units such as pounds (lb) and ounces (oz). Unlike the metric system's clean multiples of ten, conversion between imperial units is not as straightforward since it involves different ratios; for example, there are 16 ounces in a single pound.

The imperial system also uses 'tons', but it is important to know that an imperial ton, also known as a 'long ton', is different from the metric tonne. An imperial ton equals 2,240 pounds, which differs from the metric 'tonne' that is equivalent to 2,204.62 pounds. It's crucial for students to be aware that although some names of units are shared between the systems, they do not denote the same weights or masses.

Units of Measurement

Understanding the units of measurement employed in different systems is fundamental for accurately weighing and measuring masses. Units facilitate the universal communication of measure, allowing everyone to understand the quantity being referred to, regardless of where they are in the world.

It is essential to ensure accuracy in not just science and mathematics, but in everyday life. Whether you are cooking and need to measure ingredients, filling up your car with gas, or sending a spacecraft to the moon, the correct units of measurement and understanding of how to convert between them is critical. For example, a gram is suitable for measuring a bag of flour, while tons or tonnes might be used to quantify the lift capability of a crane. It's also imperative to use the correct units for the type of measurement: mass, weight, volume, length, or even energy and power, as seen in the exercise where 'kilowatt' is a unit of power, not mass or weight, demonstrating the necessity of understanding both the units themselves and the attributes they measure.