Mechanics (Physics) (Part-2)

One nanometer (1 nm) is equal to 10⁻⁹ meters (1 x 10⁻⁹ m).

SI Units (International System of Units)

Meter (m) – Base unit of distance in the SI system
Kilometer (km) – 1 km = 1,000 meters
Centimeter (cm) – 1 cm = 0.01 meters
Millimeter (mm) – 1 mm = 0.001 meters
Micrometer (µm) – 1 µm = 10⁻⁶ meters
Nanometer (nm) – 1 nm = 10⁻⁹ metersPicometer (pm) – 1 pm = 10⁻¹² meters

SI Prefixes for Small Quantities

The International System of Units (SI) uses prefixes to denote powers of 10, making it easier to express very large or very small quantities. Here's a quick reference for the prefixes listed in the options, along with their corresponding powers of 10:

Atto (a): 10⁻¹⁸
Femto (f): 10⁻¹⁵
Zepto (z): 10⁻²¹
Yocto (y): $10⁻²⁴$

Understanding these prefixes is crucial in many scientific fields, especially in physics and chemistry, where measurements often involve extremely small values. For instance, the size of an atomic nucleus is typically measured in femtometers.

Here's a breakdown of the prefixes listed in the options:

peta (P): 10¹⁵
atto (a): 10⁻¹⁸
femto (f):  10⁻¹⁵
exa (E): 10¹⁸

The prefixes 'atto' and 'femto' are used for very small quantities, while 'peta' and 'exa' are for very large quantities. A common example of 'exa' is an exabyte, which is 10¹⁸ bytes, a unit often used to measure massive amounts of data.

Displacement is a vector quantity.
It is known that the main difference between distance and displacement is that the displacement of an object can be positive, negative, or zero, but the distance is always positive.

Hence option (d) will be the correct answer.

The apparent change in the weight of the object appears to be moving up or down.
Its SI unit is kg.

Hence option (b) will be the correct answer.

Weight, on the other hand, is the force of gravity acting on an object. It's a vector quantity, having both magnitude and direction (towards the center of the gravitational body). Weight is variable because it depends on the local gravitational field. Your weight on the Moon is about one-sixth of your weight on Earth because the Moon's gravity is weaker. The formula for weight is:

$W=mg$where $W$ is weight, $m$ is mass, and $g$ is the acceleration due to gravity.
The other options are incorrect because:

(a) Mass is variable is false; mass is constant.
(b) The load is irreversible is a non-standard scientific statement and is not a property of mass or weight.

The formula for density is  density = mass / volume, or d = m/V 

When an object starts moving on some other surface, an opposing force by the surface acts on the plane of contact with the object, which acts in the opposite direction of motion of the object, this is called frictional force.