Free Law of Universal Gravitation MCQs with Answers
21 Law of Universal Gravitation MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Every two masses attract each other with a force proportional to the product of their masses and inversely proportional to the square of their separation, expressed as F = Gm₁m₂/r². Questions also involve the gravitational constant, vector direction, superposition of gravitational forces, and the distinction between gravitational force and gravitational field strength.
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21 questions · page 2 of 3
11. The value of acceleration due to gravity on moon is _ of earth.
- A. 1/4th
- B. 1/10th
- C. 2/3rd
- D. 1/6th
Explanation: This is a fact to be memorized. Gravitational acceleration on Moon is 1/6th the gravitational acceleration on Earth. Hence Option D is correct.
Correct answer: 1/6th12. Acceleration due to gravity near earth is:
- A. Non uniform
- B. Uniform
- C. Decreasing with distance
- D. Increasing with time
Explanation: The acceleration due to gravity near Earth is approximately uniform. On Earth's surface, the standard acceleration due to gravity, denoted as "g," is approximately 9.81 meters per second squared (m/s²) and is relatively constant at a given location. This means that the acceleration due to gravity remains nearly the same for objects in the vicinity of Earth's surface, regardless of their mass. However, it's worth noting that the value of "g" can vary slightly depending on your location on Earth and other factors like altitude and local geology. For example, it is slightly higher at the poles and decreases slightly as you move toward the equator due to Earth's rotation and shape. Nevertheless, these variations are relatively small, and for most practical purposes, we consider the acceleration due to gravity as uniform near Earth's surface.
Correct answer: Uniform13. On the ground, the gravitational force on a satellite is W. What is the gravitational force on the satellite when at a height R/50, where R is the radius of the Earth?
- A. 1.04 W
- B. 1.02 W
- C. 0.98 W
- D. 0.96 W
- E. 2.13 W
Explanation: Because of equality F = - m. (G.M/r ²) = - m.g one draws G = G.M/r ² = [G.M/R ²] * [1 (1+z/R)]² =g○/(1+z/R) ² ► g (z) = g○/(1+z/R) ² ▬▬▬▬▬ > W/W○ = g/g○ = (1+z/R)⁻ ² = (1 + 1/50)^-2 = 0.961
Correct answer: 0.96 W14. The dimensions of gravitational constant "G" are:
- A. [ML-2T-1]
- B. [ML-2T-2]
- C. [M2L-2T-1]
- D. [M-1L3T-2]
Explanation: Explanation: F = G (m1) (m2) / r² G = F (r²) / (m1) (m2) G = [MLT-2] [L²] / [M] [M] = [M-1L³T-2] These dimensions correspond to surface gravity or acceleration due to gravity. These dimensions correspond to force per unit mass or pressure. These dimensions correspond to the inverse of the square of a length or area.
Correct answer: [M-1L3T-2]15. The value of G at the moon as compared with its value at the earth is :
- A. Smaller
- B. Same
- C. Greater
- D. Zero
Explanation: The gravitational constant G is a fundamental constant of nature that expresses the strength of gravitational attraction between two masses. It is a universal constant, meaning it remains the same throughout the universe. Thus, the value of G is the same on the Moon as it is on Earth, or anywhere else.Options A, C, and D are incorrect because they suggest G can vary based on location, which contradicts the definition and understanding of G as a universal constant.
Correct answer: Same16. A body weighs 72 kg on the surface of the earth its weights on the surface of the moon will be:
- A. 72 kg
- B. 12kg
- C. 24 kg
- D. 0kg
Explanation: The weight of an object on the surface of the moon can be calculated using the formula:Weight on the moon = Weight on the Earth× (Acceleration due to gravity on the moon / Acceleration due to gravity on the Earth)The acceleration due to gravity on the moon is about 1/6th of that on Earth.Weight on the moon = 72kg × (⅙)= 12kgTherefore, the weight of the body on the surface of the moon will be 12kg.
Correct answer: 12kg17. The dimensions of the gravitational constant are:
- A. [M2L2T]
- B. [M-1L3T-2]
- C. [M2L-2T-2]
- D. [ML-2T-1]
Explanation: The dimensions of the gravitational constant can be expressed using the equation for Newton's law of universal gravitation:F = Gm1m2 / r²By rearranging the equation, we can determine the dimensions of G:G = Fr² / m1m2The dimensions of the gravitational constant can be derived as follows:[Force] = [Mass][Acceleration]= [Mass][Length] / [Time]3Substituting the dimensions into the equation:G = ([M][L] / [T]²) × [L]² / [M][M]G = M-1L3T-2
Correct answer: [M-1L3T-2]18. The ratio of inertial mass to the gravitational mass is equal to:
- A. 1/2
- B. 1
- C. 2
- D. No fixed number
Explanation: Inertial mass is a measure of how fast an object accelerates--given the same force, increasing the inertial mass implies decreasing acceleration. The simplest way to state the equivalence principle is this: inertial mass and gravitational mass are the same thing.The inertial mass and gravitational mass of an object are identical in value, so their ratio is 1. They differ in how they are measured. Inertial mass is measured by measuring an object's resistance to changes in velocity; while gravitational mass describes the force on an object in a gravitational field.A, C, D: These options are incorrect as they do not state the true value of the ratio i.e. 1.
Correct answer: 119. The escape velocity of body from a planet does not depend upon;
- A. The mass of a body
- B. The mass of the planet
- C. The average radius of the planet
- D. The density of the planet
Explanation: The escape velocity 'v' of a body depends upon the acceleration due to gravity of the planet and the radius of the planet but not on mass of planet.
Correct answer: The mass of a body20. A person weighting 400N at the surface of earth at particular location. When the same object is taken to a point located at higher attitude then the weight of the same person will be:
- A. Less than 400 N
- B. Less than 500 N
- C. Equal to 500 N
- D. Zero
Explanation: When the same object is taken to a point located at a higher altitude, the weight of the person will be less than 400 N. This is because weight is determined by the gravitational force exerted by the Earth, and as you move away from the surface, the gravitational force decreases. So, at a higher altitude, the person would weigh less than 400 N.
Correct answer: Less than 400 N