If the mass of an object is 74.5 kg, what is its approximate weight on Earth? (Take g = 9.8 m/s²)

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Question

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RRB JE CBT 2 (Mechanical Engineering) ReExam Official Paper (Held On: 04 Jun, 2025)

Answer 1

The Correct answer is 730 N.

Key Points

The weight of an object is the force it experiences due to gravity, calculated using the formula: Weight = Mass × Acceleration due to gravity (g).
Here, the given mass of the object is 74.5 kg, and the value of g (acceleration due to gravity) is 9.8 m/s².
Using the formula: Weight = 74.5 × 9.8 = 730.1 N.
The result is approximately 730 N, which matches the correct option.
Weight is a vector quantity, meaning it has both magnitude and direction. On Earth, the direction is toward the center of the planet.
Weight varies depending on the gravitational pull, so it would be different on other celestial bodies with different gravitational values.
The use of 9.8 m/s² as the gravitational constant is standard for calculations on Earth's surface.

Additional Information

Key Concept: Weight vs Mass
- Mass is a measure of the amount of matter in an object, and it is constant regardless of location. It is measured in kilograms (kg).
- Weight, on the other hand, is the force exerted by gravity on an object’s mass. It depends on the gravitational acceleration at a specific location and is measured in newtons (N).
Scientific Context
- The formula Weight = Mass × g is derived from Newton's Second Law of Motion, which states that Force = Mass × Acceleration.
- In the context of weight, the acceleration due to gravity (g) acts as the acceleration component.
Importance of Accurate Calculations
- Understanding weight is crucial in fields like engineering, space exploration, and physics, where precise force measurements are required.
- In everyday life, weight is used in designing structures, manufacturing, and medical applications like determining body weight.