WBBSE Solutions For Class 8 School Science Chapter 1 Physical Environment Force And Pressure Review Questions

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Chapter 1 Physical Environment Force And Pressure Review Questions MCQs

Question 1. Action and reaction forces

  1. Are not the same in magnitude
  2. Are equal in magnitude and opposite in direction
  3. Act in the same direction
  4. Cancel each other.

Answer: 2. Are equal in magnitude and opposite in direction

Question 2. A book is lying in a stationary condition on the table. The book is stationary because

  1. The weight of the book and the normal reaction is oppositely directed
  2. The force of friction is absent
  3. The weight of the book is more than the normal reaction
  4. There is no external force acting on the book.

Answer: 2. There is no external force acting on the book.

Question 3. The relation between force (f) which produces an acceleration on an object of mass (m) is

  1. A = f/m
  2. A = m/f
  3. F=m/a
  4. A = f.m

Answer: 1. A = f/m

Question 4. Using a spring balance, we measure

  1. The mass of an object
  2. The weight of an object
  3. The pressure of an object
  4. The buoyancy on an object

Answer: 2. The weight of an object

Read And Learn More WBBSE Solutions For Class 8 School Science Review Questions

Question 5. If the area of contact between two surfaces is increased, the magnitude of frictional force will

  1. Increase
  2. Decrease
  3. Remain same
  4. Vanish

Answer: 2. Decrease

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Question 6. The mass of an object is 1 kg. The weight of that object is

  1. 1 N
  2. 9.8 n
  3. 9.8 dyne
  4. 9.8 kg

Answer: 2. 9.8 n

Question 7. If the action-reaction force which acts vertically between two surfaces is increased, the frictional force will

  1. Increase
  2. Remain same
  3. Decrease
  4. Vanish

Answer: 1. Increase

Question 8. The weight of an object is 30 kg in air and 25 kg in water. What is the weight of water displaced by the object when it is immersed in water?

  1. 30 Kg
  2. 25 Kg
  3. 5 Kg
  4. None of these

Answer: 3. 5 Kg

Question 9. When completely immersed in water, the weight of an object is 30 kg and the weight of water displaced by it is 15 kg. The weight of that object in air is

  1. 45 Kg
  2. 30 Kg
  3. 15 Kg
  4. None of these

Answer: 1. 45 Kg

Question 10. When the density of a liquid increases, the pressure exerted by the liquid at any point within it

  1. Increases
  2. Decreases
  3. Remains unchanged
  4. Becomes zero

Answer: 1. Increases

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Question 11. If the depth of a point within a liquid decreases, the pressure on that point exerted by the liquid

  1. Increases
  2. Decreases
  3. Remains unchanged
  4. Becomes zero

Answer: 2. Decreases

Question 12. The density of river water is

  1. More than that of seawater
  2. Less than that seawater
  3. Same as that of seawater
  4. None of these

Answer: 2. Less than that of seawater

Question 13. 1 Atmospheric pressure is equal to the pressure exerted by a column of mercury of height

  1. 76 M
  2. 76Cm
  3. 76 Mm
  4. 10.34m

Answer: 2. 76Cm

Question 14. The density of mercury is

  1. 13.6 kg/m³
  2. 13.6 g/litre
  3. 13.6 g/cc
  4. 13.6 kg/cc

Answer: 3. 13.6 g/cc

Question 15. The pressure exerted by air is measured by

  1. Hydrometer
  2. Barometer
  3. Calorimeter
  4. Speedometer

Answer: 3. Calorimeter

Question 16. The density of an object is

  1. Weight per unit area
  2. Force to produce unit acceleration
  3. Mass per unit length
  4. Mass per unit volume

Answer: 4. Mass per unit volume

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Question 17. The buoyant force acts in

  1. Upward direction
  2. Downward direction
  3. Laterally
  4. All directions

Answer: 1. Upward direction

Question 18. When immersed in water, if the weight of water displaced by the object is more than the weight of the object in the air, then the object will

  1. Float on water
  2. Sink in water
  3. Float anywhere inside the water
  4. None of these

Answer: 1. Float on water

Question 19. Pressure at a point within a liquid

  1. Acts in a downward direction only
  2. Acts in an upward direction only
  3. Acts in all directions
  4. Acts in lateral direction only

Answer: 3. Acts in all directions

Question 20. If the weight of a body in the air is w and the buoyancy of a liquid on it is b, then in which of the following cases will the body sink when immersed in the liquid?

  1. W=b
  2. W<b
  3. W>b
  4. In all the cases

Answer: 3. W>b

Question 21. In which of the following cases will a milk bottle exert maximum pressure on the table?

  1. Position – 1
  2. Position – 2
  3. Position – 3
  4. Same in all positions

Answer: 2. Position – 2

Question 22. Absence of which of the following forces would have caused difficulty in walking?

  1. Geomagnetic force
  2. Gravitational force
  3. Electrostatic force
  4. Frictional force

Answer: 4. Frictional force

Question 23. Two balls marked a and b have the same volume but the density of the material of b is more than that of a. The balls are completely immersed in a liquid. Which of the following statements is correct?

  1. Buoyancy on b is more than on a
  2. Buoyancy is the same for both a and b
  3. Buoyancy on a is more than on b
  4. No buoyancy acts on either of the two

Answer: 4. No buoyancy acts on either of the two

Chapter 1 Physical Environment Force And Pressure Fill in the Blanks

Question 1. When 1 kg of weight is placed on an outstretched hand, the weight exerts a force of magnitude_______
Answer: 9.8 N

Question 2. Force = mass of an object _______
Answer: Acceleration

Question 3. Acceleration is the rate of change of velocity with_______
Answer: Time

Question 4. We get the idea about_______Newton’s 1″ law.
Answer: Inertia

Question 5. 9.8 Newton _______
Answer: 1

Question 6. Every action has an_______reaction.
Answer: Equal, Opposite

Question 7. The frictional force on the nature of_______surfaces in contact with each other.
Answer: Depends

Question 8. Frictional force does not depend on the of _______surface in contact with another surface.
Answer: Area

Question 9. The density of a substance is the weight of unit _______ of the substance.
Answer: Volume

Question 10. The density of concentrated saline water is_______than that of ordinary water.
Answer: More

Question 11. The density of glycerine is_______than that of water.
Answer: More

Question 12. 1 ml mercury weighs_______ water.
Answer: More

Question 13. If the density of mercury is 13.6 g/cc, the mass of 2 cc of mercury is_______g.
Answer: 27.2

Question 14. At sea level, the pressure exerted by air is equal to the pressure exerted by a mercury column of height_______cm.
Answer: 76

Question 15. At sea level, the pressure exerted by air is equal to the pressure exerted by a water column of height
than 1 ml of _______m.
Answer:10.34

Question 16. The pressure of liquid at any point inside of liquid and depends on the _______ depth of the point from the surface of the liquid
Answer: Density

Question 17. The pressure of the liquid at a point within it is the same in any_______
Answer: Direction

Question 18. Liquid seeks its own_______
Answer: Height

Question 19. When immersed in water, the weight of any object_______
Answer: Decreases

Question 20. 1 litre= _______ cubic centimeter.
Answer: 1000

Question 21. 1 Newton =_______ dyne.
Answer: 100000

Question 22. When an object is immersed in water, it acts _______ downwards and buoyancy acts upwards.
Answer: Weight

Question 23. The density of Mercury is more than water, so it _______ in water.
Answer: Sink

Question 24. The _______ exerted by water at any point within it does not depend on the shape and size of the container in which it is kept.
Answer: Pressure

Question 25. The weight of an object is 100 g in air and when immersed in water it weighs 70 g. So the weight of water displaced by the object _______g.
Answer: 30

Chapter 1 Physical Environment Force And Pressure Identify as ‘True’ or ‘False’

Question 1. SI unit of force is Newton.
Answer: True

Question 2. We get an idea about inertia from Newton’s first law.
Answer: True

Question 3. The frictional force is independent of the nature of two surfaces in contact with each other.
Answer: False

Question 4. The frictional force is independent of the surface area of an object in contact with the other surface.
Answer: True

Question 5. Pressure is the force applied per unit area of the surface.
Answer: True

Question 6. When a mass of double the weight is hung, the spring elongates by four times.
Answer: False

Question 7. Force always produces acceleration in the body on which it is applied.
Answer: False

Question 8. Air exerts no pressure.
Answer: False

Question 9. Spring balance is used to measure pressure.
Answer: False

Question 10. Force / mass = acceleration
Answer: True

Question 11. Pressure at a point within a liquid depends on the density of the liquid.
Answer: True

Question 12. Pressure at a point within a liquid depends on the depth of that point from the surface of the liquid.
Answer: True

Question 13. The pressure exerted by air is equal to the pressure exerted by a water column of a height of 10.34 meters.
Answer: True

Question 14. Static friction is smaller than sliding friction.
Answer: False

Question 15. An egg sinks in pure water but floats in concentrated saline water.
Answer: True

Question 16. Pressure at any point within the water is the same in all directions.
Answer: True

Question 17. Water exerts pressure only downwards.
Answer: False

Question 18. A buoyant force acts upwards.
Answer: True

Question 19. Buoyancy is absent in outer space.
Answer: True

Question 20. Ice floats on water.
Answer: True

Question 21. Swimming in the sea is easier than swimming in the river.
Answer: True

Chapter 1 Physical Environment Force And Pressure Match the Columns

Question 1. 

Column -A Column-B 
A. 1litre 1. 1g/cm3
B. Density of water 2. 1kg
C. mass of 1cc of water 3. 1000g
D. 1kg of water 4. 1g

Answer: A-2,B-1,C-4,D-3

Question 2.

Column-A Column-B
A. Measurement of force 1. cm/s2
B. S1 unit of force 2. Mass per unit volume
C. Cgs unit of acceleration 3. Spring Balance
D. Density 4. Newton

Answer: A-3,B-4,C-1,D-2

Question 3.

Column-A Column-B
A. A substance  floats 1. If the buoyant force is less than the weight of the substance
B. supply of water in urban areas utilizes the property 2. Density of  mercury
C. a substance sinks 3. If the buoyant force is more than the weight of the substance
D. Buoyant force 4. Liquid finds its own height

Answer: A-3,B-4,C-1,D-2

Question 4.

Column-A Column-B
A. Normal  Atmospheric pressure 1. Borameter
B. Density of mercury 2. independent of the direction
C. Pressure at any point within a liquid 3. 13.6 g/cc
D. Measurement of air pressure 4. Pressure exerted by a mercury column of height 76 cm

Answer: A-4,B-3,C-2,D-1

Question 5.

Column-A Column-B
A. A ship sinks more in 1. Water
B. A piece of ice floats in 2. Saline water
C. An iron nail sinks in 3. River water
D. Density of seawater more than that of 4. Alcohol

Answer: A-3,B-1,C-2,D-4

 

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