9th Grade Science Test
Topics: Thrust, Pressure, Weight, Buoyancy, Units, and Reasoning Questions
Multiple Choice Questions (MCQs)
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The SI unit of pressure is:
- (a) Pascal (Pa)
- (b) Newton (N)
- (c) Joule (J)
- (d) Kilogram (kg)
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Thrust is defined as:
- (a) The force exerted by a fluid on an object
- (b) The perpendicular force acting on a surface
- (c) The resistance of a surface to movement
- (d) None of the above
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Buoyant force depends on:
- (a) Mass of the object
- (b) Weight of the object
- (c) Density of the fluid
- (d) Both b and c
Assertion-Reason Questions
For questions 4 to 6, select the correct option:
- A: Both assertion and reason are true, and reason is the correct explanation of assertion.
- B: Both assertion and reason are true, but reason is not the correct explanation of assertion.
- C: Assertion is true, but reason is false.
- D: Assertion is false, but reason is true.
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Assertion: Objects float in water due to buoyant force.
Reason: Buoyant force acts downward on an object in a fluid.- (a) A
- (b) B
- (c) C
- (d) D
-
Assertion: Pressure increases with an increase in the depth of a liquid.
Reason: Liquids exert pressure only in the horizontal direction.- (a) A
- (b) B
- (c) C
- (d) D
-
Assertion: Weight of an object on the moon is less than its weight on Earth.
Reason: The gravitational force on the moon is less than that on Earth.- (a) A
- (b) B
- (c) C
- (d) D
One Mark Questions
- Define thrust and state its SI unit.
- What is the relationship between thrust and pressure?
- What happens to the pressure if the area of contact is increased, keeping the force constant?
Two Mark Questions
- Explain why objects with density less than that of water float on water.
- If the force acting on an area of 2 m² is 20 N, calculate the pressure.
Numerical Problems
- An object weighing 50 N is placed on a surface with an area of 0.5 m². Calculate the pressure exerted by the object on the surface.
- A rectangular block has dimensions of 2 m x 3 m x 4 m. If it exerts a thrust of 240 N, calculate the pressure exerted if it lies on its smallest face.
