NCERT Class 9 Science — Chapter 3: Gravitation

Which one of the following instruments is used to determine the purity of milk?

If the mass of one of two objects is doubled, the gravitational force between them:

When an object is thrown vertically upwards, the direction of the acceleration due to gravity during its ascent is:

A car falls off a ledge. Which of the following determines the time it takes to hit the ground?

Which one of the following physical quantities is a vector?

Which of the following correctly characterizes the acceleration due to gravity ($g$)?

Which of the following factors does NOT affect the value of acceleration due to gravity ($g$) at a place?

Consider the following statements about the force of gravity: 1. It decreases as we go higher in altitude from the earth's surface. 2. It is constant at all points on the earth's surface. 3. It is responsible for the rotation of the earth on its axis. Which of the statements given above is/are correct?

The weight of an object is defined as:

Who among the following scientists determined the value of the Universal Gravitation Constant ($G$)?

The value of the acceleration due to gravity ($g$) on the earth depends on: 1. The mass of the earth. 2. The atmospheric pressure on the surface. 3. The mass of the object falling. Select the correct answer using the code given below:

With reference to the concept of Pressure, consider the following statements: 1. Pressure is defined as the area acting per unit thrust. 2. For a given force, pressure increases as the area of contact decreases. 3. The SI unit of pressure is Pascal (Pa). Which of the statements given above is/are correct?

Which one of the following statements regarding the mass of an object is NOT correct?

If the distance between two objects is reduced to half, the gravitational force between them becomes:

Which of the following everyday phenomena can be explained by the concept of pressure? 1. School bags having wide straps. 2. Sharp knives cutting vegetables easily. 3. Camels running easily in deserts. 4. Tractors having wide tyres. Select the correct answer using the code given below:

Which one of the following forces is responsible for keeping an object moving in a circular path?

The foundations of high-rise buildings are kept wide primarily to:

What is the technical term for the upward force exerted by a fluid on an object immersed in it?

A stone tied to a string is whirled in a circular path. If the string suddenly breaks, the stone will move:

If a stone and a piece of paper are dropped simultaneously in a vacuum chamber, which of the following will occur?

According to Archimedes’ Principle, the upward buoyant force experienced by a body immersed in a fluid is equal to:

A sheet of paper falls slower than a stone dropped simultaneously from the same height in air primarily because of:

The "Universal Gravitation Constant" is called universal because:

Consider the following statements about 'Thrust': 1. Thrust is a force acting perpendicular to a surface. 2. The effect of thrust is independent of the area on which it acts. 3. The SI unit of thrust is Newton. Which of the statements given above is/are correct?

Consider the following statements about the density of a substance: 1. It is defined as mass per unit volume. 2. If the density of an object is less than that of a liquid, it will sink in that liquid. 3. The density of a substance is a characteristic property. Which of the statements given above is/are correct?

A plastic block released underwater rises to the surface primarily because:

With reference to the value of the Universal Gravitation Constant ($G$), consider the following statements: 1. Its value is independent of the masses of the interacting bodies. 2. Its value changes with the distance between the bodies. 3. Its SI unit is $N m^2 kg^{-2}$. Which of the statements given above is/are correct?

Which of the following remains constant for an object anywhere in the universe?

According to Newton's Third Law, an apple attracts the Earth with the same force that the Earth attracts the apple. The Earth does not appear to move towards the apple because:

Consider the following statements about the motion of a falling object: 1. The direction of motion changes continuously. 2. The magnitude of velocity changes. 3. The acceleration is constant near the earth's surface. Which of the statements given above are correct?

If a feather and a coin are dropped in a vacuum chamber:

Which of the following phenomena are successfully explained by the Universal Law of Gravitation? 1. The motion of the moon around the earth. 2. The formation of tides due to the moon and the Sun. 3. The force that binds the atmosphere to the earth. 4. The motion of planets around the Sun. Select the correct answer using the code given below:

Consider the following statements regarding the Universal Law of Gravitation: 1. The force is directly proportional to the product of the masses of two objects. 2. The force is inversely proportional to the distance between the two objects. 3. The force acts perpendicular to the line joining the centres of the two objects. Which of the statements given above is/are correct?

With reference to the motion of the moon around the earth, consider the following statements: 1. The motion of the moon is an example of uniform motion with zero acceleration. 2. The force responsible for this motion is directed towards the centre of the earth. 3. In the absence of this force, the moon would move in a straight line tangent to its circular path. Which of the statements given above is/are correct?

With reference to the acceleration due to gravity ($g$) of the earth, consider the following statements: 1. The earth is a perfect sphere, ensuring a constant value of $g$ on its surface. 2. The value of $g$ is greater at the poles than at the equator. 3. The value of $g$ increases as the radius of the earth increases. Which of the statements given above is/are correct?

An object weighs less on the Moon than on the Earth because:

Consider the following statements regarding Buoyancy: 1. It is the upward force exerted by a fluid on an immersed object. 2. The magnitude of the buoyant force is independent of the density of the fluid. 3. An object sinks if the buoyant force is greater than its weight. Which of the statements given above is/are correct?

Consider the following statements about Mass and Weight: 1. Mass is a measure of inertia and remains constant everywhere. 2. Weight is a scalar quantity that does not depend on the gravitational force. 3. The weight of an object is zero in outer space, but its mass remains the same. Which of the statements given above are correct?

Which of the following instruments are based on Archimedes’ Principle? 1. Lactometers 2. Hydrometers 3. Odometers 4. Barometers Select the correct answer using the code given below:

A cork floats on water while an iron nail of the same mass sinks. This is best explained by the fact that:

Consider the following statements regarding the gravitational force between two objects: 1. It is always attractive in nature. 2. It acts perpendicular to the line joining the centres of the two objects. 3. It forms an action-reaction pair. Which of the statements given above are correct?

Consider the following statements regarding the force of gravitation: 1. It is a contact force that requires physical touching of objects. 2. It is a weak force unless large masses are involved. 3. It is a repulsive force. Which of the statements given above are correct?

Consider the following statements regarding the elongation of a rubber string suspending a stone: 1. The elongation is due to the magnetic force of the stone. 2. The elongation decreases when the stone is immersed in water. 3. The decrease in elongation is due to the buoyant force acting upwards. Which of the statements given above are correct?

Consider the following statements regarding the Universal Law of Gravitation: 1. It applies to celestial bodies like planets and stars. 2. It does not apply to terrestrial objects with small masses. 3. The force is always attractive. Which of the statements given above is/are correct?

Which of the following pairs is correctly matched?

Which of the following best explains why a sharp knife cuts better than a blunt one?

The SI unit of Pressure is named after which scientist?

Which one of the following forces is primarily responsible for holding the atmosphere around the Earth?

The value of $g$ is maximum at:

Why is the gravitational force between two ordinary objects, such as two people, not perceptible in daily life?

When a body is floating on a liquid, the weight of the body is balanced by:

The SI unit of density is:

The relative density of a substance is defined as the ratio of:

The SI unit of Thrust is:

The pressure exerted by a liquid at a certain depth depends on:

The upward force experienced by a body immersed in a fluid is attributed to which of the following phenomena?

With reference to the motion of objects under the influence of earth's gravitational force, consider the following statements: 1. In a vacuum, heavier objects fall faster than lighter objects. 2. Air resistance offers friction to the motion of falling objects. 3. The gravitational force experienced by an object is directly proportional to its mass. Which of the statements given above is/are correct?

An object is thrown vertically upwards. At the highest point of its path:

An iron nail sinks in water because:

Consider the following statements regarding 'Free Fall': 1. During free fall, the direction of motion of the object changes continuously. 2. The acceleration experienced by an object in free fall is independent of its mass. 3. Free fall occurs when an object falls towards the earth under gravitational force alone. Which of the statements given above are correct?

Consider the following statements regarding the density of water and floating objects: 1. If an object has a density greater than water, it will float. 2. If an object has a density less than water, it will float. 3. The density of water is approximately $100 kg m^{-3}$. Which of the statements given above is/are correct?

With reference to the pressure exerted by fluids, consider the following statements: 1. Fluids exert pressure only on the base of the container. 2. Pressure exerted in any confined mass of fluid is transmitted undiminished in all directions. 3. Fluids have weight and thus exert pressure. Which of the statements given above are correct?

Which of the following statements is correct regarding the direction of the buoyant force?