Question

How much would a 70kg man weigh on the moon? What will be his mass on earth and on the moon? $g=1.7m{{s}^{-2}}$ on the moon.

Answer 1

Hint: Let us find the weight of the mass on the moon as weight is the product of mass and the acceleration due to gravity of the planet. Next, the mass of the body remains the same and is independent of the place where it is. The weight changes as the acceleration of gravity changes. Therefore, we can find the weight of the man on both the moon and earth easily.
Formulas used:
$W=mg$

Complete answer:
Let us first find the mass of the man on the moon.
As mass is independent of the place where it is, the mass remains constant wherever.
Therefore, the weight of the man on earth can be calculated as,
$\begin{align}
  & W=mg \\
 & \Rightarrow W=70\times 10 \\
 & \Rightarrow W=700N \\
\end{align}$
Similarly, the acceleration due to gravity on moon is given in the question above,
Therefore, the weight of the same man on moon will be,
$\begin{align}
  & W=mg \\
 & \Rightarrow W=70\times 1.7 \\
 & \Rightarrow W=119N \\
\end{align}$
In this way, we can find the weight of the same object if the mass and the acceleration of gravity at respective planets is given.

Additional information:
g is the friction-less, free-fall acceleration sustained by the sampling mass m under the attraction of the gravitational source. It is a vector oriented toward the field source, of magnitude measured in acceleration units. The gravitational acceleration vector depends only on how massive the field source M is and on the distance 'r' to the sample mass m. It does not depend on the magnitude of the small sample mass. Newton's law of universal gravitation states that there is a gravitational force between any two masses that is equal in magnitude force each mass, and also this force is aligned to draw two masses towards each other. The force go gravitation depends on the masses of the two objects and is inversely proportional to the square of the distance between them.

Note:
There is a lot of difference between mass and weight of any object, the mass of the object is not equal to the weight. The weight is the force applied by the body on the ground. Weight of an object changes from planet to other planet but mass is always the same. Weight depends on the gravitational acceleration but mass is independent of acceleration of gravity.