Question

The force by which the body is attracted towards the centre of the earth is called: ____.

• A. impulsive force
• B. mass
• C. weight
• D. momentum

Hint:

Since Weight is a force, its SI unit is the Newton (N), not the kilogram. If you weigh yourself on a scale, the scale is actually measuring Newtons and then converting it to kilograms for you!

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Gravity is a universal force of attraction between masses. For objects on or near a planet, this gravitational pull acts as an external force pulling the object toward the planet's center.

Step 2: Key Formula or Approach:
The gravitational force $W$ is calculated using Newton's Second Law: \[ W = m \times g \] where $m$ is mass and $g$ is the acceleration due to gravity.

Step 3: Detailed Explanation:
The weight of an object is the specific name given to the force of gravity acting upon it. Because weight is a force, it is a vector quantity directed toward the center of the Earth. Its value depends on the local strength of gravity ($g$). On Earth, $g \approx 9.8 \text{ m/s}^2$, but on the Moon, where gravity is weaker, your weight would be about $1/6$th of your Earth weight, even though your mass remains unchanged.

Step 4: Final Answer:
The force of attraction toward the Earth's centre is called weight.

Answer 2

The question describes the force by which a body is attracted towards the centre of the earth. We can check each option by asking two things: is it actually a force, and if so, is it specifically the force of gravitational attraction toward Earth's centre?

1. Impulsive force: This is a force, but it refers to any large force acting over a very short duration, such as a hammer blow or a collision impact. It is a general category of force unrelated specifically to gravity or to Earth's centre.
2. Mass: Mass is not a force at all, it is a scalar quantity describing the amount of matter in a body, and it does not have a direction, let alone a direction toward Earth's centre.
3. Weight: Weight is specifically defined as the gravitational force with which the Earth attracts a body toward its centre. It is a force, measured in newtons, and unlike a generic force, it is defined precisely as this Earth-directed gravitational pull, matching the description exactly.
4. Momentum: Momentum is not a force either, it is the product of an object's mass and velocity, describing its quantity of motion, not any attraction toward Earth's centre.

Only weight satisfies both conditions, being a force, and specifically the gravitational one directed toward the Earth's centre.

Therefore, the correct answer is weight.