Imp Questions For All Chapters – General Science Class 8
Short Questions
1. What is force?
- Force is a push or pull on an object.
2. What is the SI unit of force?
- The SI unit of force is Newton (N).
3. What are the two types of forces?
- Contact forces and non-contact forces.
4. Give two examples of contact force.
- Muscular force and frictional force.
5. Give two examples of non-contact force.
- Gravitational force and magnetic force.
6. What is friction?
- Friction is the force that opposes motion.
7. What is inertia?
- Inertia is the tendency of an object to resist change in motion.
8. Give an example of inertia of rest.
- A book remains on a table until pushed.
9. Give an example of inertia of motion.
- A moving car stops slowly after brakes are applied.
10. What is pressure?
- Pressure is force applied per unit area.
11. What is the SI unit of pressure?
- The SI unit of pressure is Pascal (Pa).
12. How does pressure change with area?
- Smaller area increases pressure, larger area decreases pressure.
13. Why do sharp knives cut better than blunt ones?
- Sharp knives apply more pressure with less force.
14. What is buoyant force?
- The upward force exerted by a fluid on an object.
15. Why do objects float in water?
- If buoyant force is greater than the object’s weight, it floats.
16. What is atmospheric pressure?
- The pressure exerted by air around the Earth.
17. Why do camels have broad feet?
- Broad feet reduce pressure, preventing sinking in sand.
18. What happens to pressure as we go higher?
- Atmospheric pressure decreases with height.
19. Which scientist discovered buoyant force?
- Archimedes discovered buoyant force.
20. Why do heavy trucks have many wheels?
- More wheels distribute weight and reduce pressure.
Long Questions
1. What is the difference between contact and non-contact forces?
- Contact forces act when objects touch, like friction and muscular force. Non-contact forces act from a distance, like gravitational and magnetic force.
2. What is friction and how is it useful?
- Friction is the force that opposes motion between two surfaces. It helps us walk, hold objects, and stop moving vehicles.
3. How does pressure depend on force and area?
- Pressure increases if force increases or area decreases. That is why knives have sharp edges and elephants have broad feet.
4. What is buoyant force and why do objects float?
- Buoyant force is the upward push of a liquid on an object. Objects float if this force is greater than their weight.
5. What is inertia and how does it affect motion?
- Inertia is an object’s tendency to stay at rest or keep moving. A bus suddenly stopping makes passengers fall forward due to inertia.
6. Why do dams have thick walls at the bottom?
- Water pressure increases with depth, so dams are made thicker at the base to withstand high pressure.
7. What is atmospheric pressure and how does it change?
- Atmospheric pressure is the weight of air around us. It decreases as we go higher above sea level.
8. How does Archimedes’ principle help in shipbuilding?
- Archimedes’ principle states that an object in water experiences an upward force equal to the weight of displaced water. Ships float because they displace enough water to balance their weight.
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