Question

The weight of a body is $2.0\,N$. What is the mass of the body? (\[g = 10{\text{ }}\,m{s^{ - 2}}\])
A. 20 kg
B. 2 kg
C. 5 kg
D. 0.2 kg

Answer 1

Hint: Newton's laws of motion are three laws that define the connection between an object's motion and the forces acting on it in classical mechanics. Unless it is acted upon by an external force, the first law says that an object either remains at rest or continues to travel at a constant pace. We use this concept here.

Formula used:
\[F{\text{ }} = {\text{ }}ma\]
Where, $F$ = force, $m$ = mass and $a$ = acceleration.

Complete answer:
The second law says that the rate of change in momentum of an item is exactly proportional to the force applied, or that the net force on an object is equal to the mass multiplied by the acceleration for an object of constant mass. The second law says that the rate at which a body's momentum changes over time is proportionate to the force applied and happens in the same direction as the applied force.

Newton's rules apply exclusively to a certain set of reference frames known as Newtonian or inertial reference frames. According to certain writers, the first law defines an inertial reference frame; thus, the second rule applies only when the observation is made from an inertial reference frame, therefore the first law cannot be established as a particular instance of the second.

Others consider the first law to be a consequence of the second. Long after Newton's death, the explicit idea of an inertial frame of reference was established.
We know that \[F = mg\]
$ \Rightarrow m = \dfrac{F}{g}$
Given Force is 2.0 N
It is given that \[g = 10{\text{ }}m{s^{ - 2}}\]
Substituting the values
$ \Rightarrow m = \dfrac{2}{{10}}$
$ \therefore m = 0.2{\text{ }}kg$

Hence option D is correct.

Note: Note that the value of g is \[{\text{9}}{\text{.8 }}m{s^{ - 2}}\]. We use the given value of g as \[{\text{10 }}m{s^{ - 2}}\] since it is given in the question. Some further include a fourth rule, which asserts that forces accumulate like vectors, or that forces obey the concept of superposition, which is inferred but never stated by Newton. Newton's laws of motion, in their original form, are insufficient to describe the motion of rigid and deformable bodies.