Q31. Under which of the following conditions is the work done by a force equal to zero?
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 31–40 of 200 questions
Q32. If the velocity of a moving body is doubled, its kinetic energy becomes:
Explanation
Kinetic energy is calculated using the formula one-half mass times the square of velocity. Because the velocity term is squared, any change in speed has a non-linear effect on the energy. Doubling the velocity of an object results in a factor of two squared, which means the kinetic energy increases to four times its original value, assuming the mass remains constant.
Q33. Which of the following represents the commercial unit of electrical energy?
Explanation
The kilowatt-hour is the standard unit used by utility companies to measure and bill electrical energy consumption. It represents the energy consumed by a one-thousand-watt appliance operating for one hour. While the Joule is the standard SI unit for energy, it is too small for practical commercial use. One kilowatt-hour is equivalent to three point six million Joules of electrical energy.
Q34. Consider the following statements regarding energy transformations:
I. In an electric generator, mechanical energy is converted into electrical energy.
II. In an electric motor, electrical energy is converted into mechanical energy.
III. In a solar cell, solar energy is converted into electrical energy.
IV. In a microphone, electrical energy is converted into sound energy.
V. In a battery, chemical energy is converted into electrical energy.
Which of the above statement(s) is/are incorrect?
I. In an electric generator, mechanical energy is converted into electrical energy.
II. In an electric motor, electrical energy is converted into mechanical energy.
III. In a solar cell, solar energy is converted into electrical energy.
IV. In a microphone, electrical energy is converted into sound energy.
V. In a battery, chemical energy is converted into electrical energy.
Which of the above statement(s) is/are incorrect?
Explanation
Most energy transformations are correctly described: generators convert mechanical to electrical energy, motors do the reverse, solar cells use light, and batteries use chemical energy. However, a microphone actually converts sound energy into electrical signals, not the other way around. A loudspeaker is the device that converts electrical energy back into sound, making the statement about microphones technically inaccurate here.
Q35. When a simple pendulum swings from its mean position to its extreme position, what happens to its energy?
Explanation
At the mean position, a swinging pendulum possesses maximum kinetic energy and minimum potential energy. As it moves toward the extreme position, its height increases and its speed decreases. This process converts kinetic energy into gravitational potential energy. At the highest point of the swing, the pendulum momentarily stops, and its energy is entirely potential before it begins the return journey downward.
Q36. One horsepower (hp) is equivalent to approximately how many watts?
Explanation
Horsepower is a unit of power originally developed to compare the output of steam engines with the power of draft horses. In the metric system, one mechanical horsepower is defined as approximately seven hundred and forty-six watts. This unit is still commonly used today in the automotive and industrial sectors to describe the power ratings of internal combustion engines and large electric motors.
Q37. The work done in lifting a 10 kg object to a height of 5 meters (taking g = 9.8 m/s2) is:
Explanation
Work done in lifting an object against gravity is equal to the product of its mass, the acceleration due to gravity, and the height. For a ten-kilogram object lifted five meters with gravity at nine point eight meters per second squared, the calculation results in four hundred and ninety Joules. This value represents the gravitational potential energy gained by the object during lift.
Q38. The law of conservation of energy states that:
Explanation
The law of conservation of energy is a fundamental principle stating that energy cannot be created or destroyed within an isolated system. Instead, it can only change from one form to another, such as potential energy becoming kinetic energy. Consequently, the total amount of energy remains constant over time, ensuring that energy is always accounted for during any physical process.
Q39. Match the devices in List I with their corresponding energy conversions in List II.
| Device | Energy Conversion |
|---|---|
| A. Loudspeaker | i. Light to Chemical |
| B. Dynamo | ii. Heat to Mechanical |
| C. Photosynthesis | iii. Electrical to Sound |
| D. Steam Engine | iv. Mechanical to Electrical |
Explanation
Loudspeakers convert electrical signals into sound energy. Dynamos transform mechanical motion into electrical energy. Photosynthesis is a biological process that converts light energy from the sun into chemical energy stored in glucose. Steam engines utilize heat from burning fuel to produce mechanical work. These examples demonstrate the diverse ways in which energy is transformed to perform useful functions in technology.
Q40. Work done by kinetic friction on a moving object is always:
Explanation
Kinetic friction always acts in the direction opposite to the displacement of a moving object. Because the force and displacement vectors are in opposite directions, the work done by friction is mathematically negative. This negative work indicates that energy is being removed from the object’s kinetic energy and typically dissipated as heat, causing the object to slow down unless another force acts.Answer key for these questions
| Q | Correct answer |
|---|---|
| 31 | (a) When the force is perpendicular to the direction of displacement |
| 32 | (c) Four times the original |
| 33 | (b) Kilowatt-hour |
| 34 | (c) IV only |
| 35 | (c) Kinetic energy is converted into potential energy |
| 36 | (b) 746 W |
| 37 | (c) 490 J |
| 38 | (b) Energy can only be transformed, not created or destroyed |
| 39 | (a) A-iii, B-iv, C-i, D-ii |
| 40 | (b) Negative |
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.