Force and Pressure Quiz - CBSE Class 8 Science

Free practice quiz: Force and Pressure (CBSE Class 8 Science). 18 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following is NOT a unit of force?

   1. Newton
   2. Kilogram
   3. Dyne
   4. Pound
   Show answer

   Answer: B. Kilogram

   Kilogram is a unit of mass, not force. Newton, Dyne, and Pound are units of force.

2. A sharp knife cuts better than a blunt knife because:

   1. It is stronger
   2. It is heavier
   3. It applies more force
   4. It applies pressure over a smaller area
   Show answer

   Answer: D. It applies pressure over a smaller area

   A sharp knife concentrates the force on a smaller area, resulting in higher pressure.

3. Describe how hydraulic brakes work, relating it to principles of force and pressure.

   1. They use electricity to stop the car.
   2. They use friction to slow down the car.
   3. They use a small force to create a large pressure, stopping the car.
   4. They use magnetism to stop the car.
   Show answer

   Answer: C. They use a small force to create a large pressure, stopping the car.

   Hydraulic brakes utilize Pascal's principle: pressure applied to a confined fluid is transmitted equally throughout the fluid. A small force applied to a small piston generates high pressure in the fluid, which is then amplified by larger pistons at the wheels to generate a large braking force.

4. A block of wood floats on water, while a block of iron sinks. Explain this difference using the concept of density and pressure.

   1. Wood is lighter than iron.
   2. Wood is less dense than water, while iron is denser than water.
   3. Wood has more surface area than iron.
   4. Wood has more pressure than iron.
   Show answer

   Answer: B. Wood is less dense than water, while iron is denser than water.

   Objects float if their density is less than the density of the fluid they are in. Wood's density is less than water's, while iron's is greater.

5. Why do dams have thicker walls at the bottom than at the top?

   1. For aesthetic reasons.
   2. The water pressure increases with depth.
   3. The water pressure decreases with depth.
   4. To make the dam stronger.
   Show answer

   Answer: B. The water pressure increases with depth.

   Water pressure increases with depth, requiring thicker walls at the bottom to withstand the greater pressure.

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