WBBSE Class 8 Science Chapter 1 Force And Pressure VSAQs
Chapter 1 Physical Environment Force And Pressure VSAQ
Question 1. What is the unit of force in the SI and CGS units?
Answer:
The unit of force in the SI unit is Newton and CGS unit is done.
Question 2. What is the relation between force and acceleration?
Answer:
Force = mass x acceleration
Question 3. What do you mean by a force of 1 Newton?
Answer:
Force Of 1 Newton:-
This is the force that produces an acceleration of 1 m/s² when applied to an object of mass 1 kg.
WBBSE Class 8 Science Chapter 1 Force and Pressure VSAQs
Question 4. What do you mean by a force of 1 dyne?
Answer:
Force Of 1 dyne:-
This is the force that produces an acceleration of 1 cm/s² when applied to an object of mass 1g.
Question 5. From which law do we get an idea of inertia?
Answer:
From Newton’s first law we get an idea about inertia.
WBBSE Class 8 Force and Pressure very short answer questions
Question 6. What is the force exerted by a mass of 1 kg placed on the hand?
Answer:
The force exerted by a mass of 1 kg on our hand is 9.8 N.
Question 7. Which instrument is used to measure the weight of an object?
Answer:
A spring balance is used to measure the weight of an object.
Question 8. Do action and reaction force act on the same object?
Answer:
No, action and reaction force act on different objects.
Question 9. Which principle has been applied to make spring balance?
Answer:
If a force is applied, the spring is elongated in the direction of the applied force and the extension produced in a spring by a force is directly proportional to the applied force. This principle has been used to make spring balance.
West Bengal Class 8 Physical Science Chapter 1 Very Short Answer Questions
Question 10. What do you mean by the density of a substance?
Answer:
Density Of A Substance:-
The density of a substance is the mass of a unit volume of that substance.
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Question 11. What is the CGS and SI unit of density?
Answer:
The CGS unit of density is g/cc and its SI unit is kg/m³.
Question 12. If there is a hole at the bottom of a boat, why does water enter through it?
Answer:
Due to an upward force at any point within the water, the water enters through the hole at the bottom of the boat.
Question 13. When a ball is thrown along the surface of the table, it ultimately stops after covering some distance. Why?
Answer:
When a ball is thrown along the surface of the table with an initial velocity, it stops ultimately, because of the frictional force exerted by the surface of the table which opposes the motion of the ball.
Question 14. If the density of a liquid is increased how it will affect the buoyant force?
Answer:
If the density of a liquid is increased its buoyant force will increase.
Class 8 Science Force and Pressure VSAQs WBBSE
Very short answer questions on force and pressure for Class 8
Question 15. Write the condition of floatation.
Answer:
Floatation:-
If the weight of the object is less than the weight of the liquid displaced by it when it is immersed in the liquid, then the object will float on the liquid.
Question 16. Which instrument is used to measure the air pressure?
Answer:
A barometer is used to measure air pressure.
Question 17. To supply water in urban areas which property of the liquid is utilized?
Answer:
A liquid seeks its own height. This property is utilized in supplying water from a storage tank in urban areas.
Question 18. What will be the acceleration produced if a force of 10N acts on a mass of 5 kg?
Answer:
Acceleration = Force/ mass 10N/5kg = 2m/s².
Question 19. A floating body is weightless – why?
Answer:
A floating body is weightless
When a body floats in a liquid, the buoyant force acting upward balances the weight of the body acting downwards.
In the state of floatation, the body appears to lose its weight totally and so it is said that a floating body is weightless.
Question 20. What is the relation between the pressure exerted by a liquid and its density?
Answer:
Pressure at a point inside a liquid varies directly with the density of the liquid.
Question 21. A body is floating with a part of it submerged in a liquid. What is the relation between the weight of the body and the weight of the displaced liquid?
Answer:
Following the condition of floatation, at equilibrium, the total weight of the body is equal to the weight of the liquid displaced by the submerged volume of the body.
WBBSE Solutions for Class 8 Science Chapter 1 VSAQs
Question 22. If a body does not move on the surface of a table even if it is pulled by a force, then what kind of opposing force act on the body?
Answer:
Static Friction
WBBSE Chapter 1 quick answer solutions
Question 23. A 5N force creates a pressure of 500 Pa when it acts on a surface. What is the area of the surface in square cm?
Answer:
Area = Force/Pressure =5N / 500 Pa =1 / 100m²= 100 x 100 / cm² = 100 cm².
Question 24. The reading of a spring balance shows 10g-wt when a solid is half immersed in water. What will be the reading of the spring balance when the solid is completely immersed in water?
Answer:
Less than 10g wt due to more buoyancy.
Force and Pressure Chapter 1 VSAQs for Class 8 WBBSE
Question 25. A body kept on the floor, just tends to move when it is pulled with a force of 5N. What is the limiting force of static friction between the body and the floor?
Answer:
5N
Question 26. A car is moving towards the east. What will be the direction of frictional force acting on this car due to the surface of the road?
Answer:
Since friction always opposes the motion, Hence it will act towards the west.
Question 27. A body of mass 2kg is moving with a velocity of 15m/s. Find the momentum of the body.
Answer:
Given:
A body of mass 2kg is moving with a velocity of 15m/s.
Momentum = mass x velocity = 2kg x 15 m/s = 30 kg m/s.
WBBSE Solutions for Class 8 Science Chapter 1 VSAQs
WBBSE Class 8 Science practice very short answer questions
Question 28. The same body is immersed in two liquids A and B in succession. The extent to which the body sinks in liquid B is less than that in liquid A. What can you conclude about the densities of two liquids from the observation?
Answer:
Since a denser liquid will produce more buoyancy hence more the density of the liquid, the less the body sinks in liquid. Thus the density of liquid B is more than the density of liquid A.