Q21. According to the universal law of gravitation, the force between two objects is inversely proportional to:
Basics of Everyday Science: RAS Prelims MCQs
200 RAS Prelims MCQs on the basics of everyday science test the scientific method, the laws of motion, chemical bonding and the cell theory. The questions use daily-life examples, such as the recoil of a gun and the orbit of a satellite, and the explanations give the principle behind each example so that you can reason out similar questions.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 21–30 of 200 questions
Q22. Consider the following statements about mass and weight:
I. Mass is a scalar quantity, while weight is a vector quantity.
II. The mass of a body remains constant everywhere in the universe.
III. Weight is the gravitational force acting on an object.
IV. A body can have zero mass but non-zero weight in space.
Which of the above statement(s) is/are correct?
I. Mass is a scalar quantity, while weight is a vector quantity.
II. The mass of a body remains constant everywhere in the universe.
III. Weight is the gravitational force acting on an object.
IV. A body can have zero mass but non-zero weight in space.
Which of the above statement(s) is/are correct?
Explanation
Mass is a fundamental scalar property representing the amount of matter in an object and remains constant regardless of location. Weight is a vector quantity representing the gravitational force acting on that mass and varies based on gravity’s strength. While weight can become zero in certain conditions, such as deep space, mass can never be zero for any physical object or body.
Q23. The acceleration due to gravity (g) on the surface of the Earth is maximum at:
Explanation
Acceleration due to gravity varies across the Earth’s surface due to its flattened shape and rotation. The planet is an oblate spheroid, meaning the distance from the center to the surface is shortest at the poles. Because gravitational pull is stronger when closer to the center, the value of g reaches its maximum at the poles and its minimum at the equator.
Q24. When an object undergoes free fall near the Earth’s surface (ignoring air resistance), its:
Explanation
During free fall in a vacuum near the Earth’s surface, all objects experience a constant acceleration due to gravity, approximately 9.8 meters per second squared. While the velocity of the falling object increases uniformly over time, the rate at which it speeds up remains the same. Air resistance is ignored in this idealized model to focus on pure gravitational influence on motion.
Q25. The minimum initial velocity required for an object to escape the Earth’s gravitational pull is approximately:
Explanation
Escape velocity is the minimum speed an object must reach to break free from a planet’s gravitational field without further propulsion. For Earth, this value is approximately 11.2 kilometers per second. If an object is launched at this speed, its kinetic energy will exactly balance its gravitational potential energy, allowing it to move infinitely far away from the Earth’s pull.
Q26. Who was the first scientist to experimentally determine the value of the universal gravitational constant (G)?
Explanation
Henry Cavendish was the first scientist to accurately measure the value of the universal gravitational constant, known as G, using a torsion balance. His famous 1798 experiment allowed for the calculation of the Earth’s density and mass. While Isaac Newton formulated the law of universal gravitation, he did not experimentally determine the specific value of the constant required for calculations.
Q27. Astronauts in low Earth orbit experience "weightlessness" because:
Explanation
Astronauts in orbit experience weightlessness not because gravity is absent, but because they and their spacecraft are in a state of continuous free fall towards Earth. As they move forward at high speed, the planet’s surface curves away at the same rate they fall. This creates an environment where no normal force acts between the astronauts and their surroundings.
Q28. Consider the following planets:
I. Jupiter
II. Mars
III. Earth
Which of the following represents the correct arrangement of these planets in increasing order of their surface gravity?
I. Jupiter
II. Mars
III. Earth
Which of the following represents the correct arrangement of these planets in increasing order of their surface gravity?
Explanation
Surface gravity depends on a planet’s mass and radius. Mars has a lower mass than Earth, resulting in weaker gravitational pull. Jupiter, being the most massive planet in the solar system, possesses the strongest surface gravity among the three. Therefore, the correct sequence from the weakest to the strongest gravitational force is Mars, followed by Earth, and then Jupiter as the highest.
Q29. Kepler’s second law of planetary motion, the law of equal areas, is a consequence of the conservation of:
Explanation
Kepler’s second law states that a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. This phenomenon is a direct consequence of the conservation of angular momentum in a central force field. As a planet moves closer to the Sun, its orbital speed increases to ensure its total angular momentum remains constant throughout its orbit.
Q30. Which of the following is an exception to the rule that all massive bodies fall at the same rate in a vacuum?
Explanation
In a vacuum, where air resistance is absent, all objects experience the same acceleration due to gravity regardless of their mass or shape. This principle, famously demonstrated by Galileo, confirms that a feather and a heavy coin will hit the ground simultaneously when dropped from the same height. Therefore, there are no exceptions to this rule in a truly friction-free environment.Answer key for these questions
| Q | Correct answer |
|---|---|
| 21 | (c) The square of distance between their centers |
| 22 | (a) I, II and III |
| 23 | (d) The poles |
| 24 | (a) Acceleration remains constant |
| 25 | (b) 11.2 km/s |
| 26 | (a) Henry Cavendish |
| 27 | (d) They are in a constant state of free fall towards the Earth |
| 28 | (a) II, III, I |
| 29 | (c) Angular momentum |
| 30 | (d) There is no exception; all objects fall at the same rate in a vacuum |
Key facts from Basics of Everyday Science
- Inductive reasoning draws a general conclusion from specific observations; a control variable is kept constant in an experiment; communicating the results is the last step of the scientific method.
- Newton’s second law relates force, mass and acceleration; the recoil of a gun illustrates the third law.
- Momentum is the product of mass and velocity; impulse is equal to the change in momentum.
- A satellite in uniform circular orbit is held by the centripetal force provided by gravity.
- Water (H₂O) and N₂ show covalent bonding; sodium chloride, MgO and CaF₂ are ionic.
- The classical cell theory does not say that all cells have a true nucleus.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Basics of Everyday Science?
This page has 200 practice MCQs on Basics of Everyday Science (Science and Technology). Each has the correct answer, and most have an explanation.
What is the product of mass and velocity called?
Momentum. Newton’s second law says that the rate of change of momentum is equal to the force applied, and impulse is equal to the change in momentum of a body.
Which law explains the recoil of a gun?
Newton’s third law of motion. The gun pushes the bullet forward, and the bullet pushes the gun back with an equal and opposite force, which is felt as recoil.
What holds a satellite in a circular orbit?
The centripetal force provided by gravity. The Earth’s pull keeps changing the direction of the satellite’s velocity so that it moves in a circle and does not fly off in a straight line.