## Chapter 1 Physical Environment MCQ Questions

Question 1. If you have a mass of 40 Kg, then the force with which the earth attracts you towards its centre is

- 20 N
- 40 N
- 392 N
- 336 N

Answer: 3. 392 N

Question 2. If the mass of two objects is doubled, the force due to gravitation

- Increases by two times
- Increases by four times
- Decreases by four times
- Decreases by two times

Answer: 2. Increases by four times

Question 3. The mathematical expression of the Law of Universal Gravitation is

Answer:

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

4. Using a spring balance, we measure

- The mass of an object
- The weight of an object
- The pressure of an object
- The acceleration due to gravity at a place

Answer: 2. The weight of an object

Question 5. The weight of an object on earth is the product of its mass and

- G
- g
- Distance from the centre of the earth
- None of these

Answer: 2. g

Question 6. F (the gravitational force) is zero when the distance between two objects is

- Zero
- Infinitely large
- Less than the radius of the earth
- Does not depend on the distance between the two objects

Answer: 2. Infinitely large

Question 7. The magnitude of escape velocity is

- 11.2 km/s
- 11.2 m/s
- 11.2 cm/s
- 11.2 km/h

Answer: 1. 11.2 km/s

8. The value of G in SI unit is

Question 9. If the acceleration due to gravity on earth is “g”, its value on the moon is

- g/6
- g
- 6g
- 0

Answer: 1. g/6

Question 10. When an ebonite rod is rubbed with wool, it acquires

- Negative charge
- No charge
- Positive charge
- Protons

Answer: 1. Negative charge

Question 11. Keeping masses of two bodies constant, if the distance between them is made twice then the gravitational force of attraction between them becomes

- Twice the previous
- Four times the previous
- Half of previous
- A fourth of previous

Answer: 2. Four times the previous

Question 12. The weight of a freely falling object

- Gradually increases
- Gradually decreases
- Remains same
- Vanishes

Answer: 3. Gradually decreases

Question 13. The net charge in an atom is

- Negative
- Zero
- Positive
- None of these

Answer: 2. Zero

Question 14. Two identical metal spheres A and B are placed on insulating stands and kept in contact as shown. What kind of charges will appear on A and B when a negatively charged ebonite rod is brought near A ? Ebonite rod

- Both A and B will have a positive charge
- Both A and B will have a negative charge
- A will have a negative charge and B a positive charge
- A will have a positive charge and B a negative charge

Answer: 4. A will have a positive charge and B a negative charge

Question 15. The CGS unit of charge is

- Coulomb
- Statcoulomb
- E.S.U.
- Ampere

Answer: 3. E.S.U.

Question 16. An atom is electrically neutral because

- The number of protons is the same as the number of electrons
- The number of protons is the same as the number of neutrons
- The number of neutrons is the same as the number of electrons
- Atom does not exhibit static electricity

Answer: 1. Number of protons is the same as the number of electrons

Question 17. Keeping the distance between the two point- charges fixed, if the amount of charge on the point charges increases,

- The electrostatic force increases
- The electrostatic force decreases
- The electrostatic force remains unchanged
- It is independent of the magnitude of charges

Answer: 1. The electrostatic force increases

Question 18. The magnitude of the electrostatic force between two point charges

- Depends on the intervening medium
- Is independent of the distance between them
- Is independent of the charge on the point- charges
- All of these

Answer: 1. Depends on the intervening medium

Question 19. When no charge is supplied to or removed from a neutral body, then the amount of

- Positive charge > negative charge present in it
- Positive charge < negative charge present in it
- Positive charge = negative charge present in it
- No charge is present in the body initially

Answer: 3. positive charge < negative charge present in it

Question 20. The law of gravitation gives the gravitational force between

- Earth and the sun only
- Earth and point mass only
- Two charged bodies only
- Any two bodies having a certain mass

Answer: 4. Any two bodies having a certain mass

Question 21. Two objects of different masses falling freely near the surface of the moon would

- Have the same velocities at any instant
- Have different accelerations
- Experience forces of different magnitudes
- undergo different distances at the same interval of time

Answer: 1. Have the same velocities at any instant

## Chapter 1 Physical Environment Fill in the Blanks

Question 1. The earth pulls any object near it by the force of _______.

Answer: Gravity

Question 2. Weight = mass of an object x _______

Answer: Acceleration due to gravity

Question 3. The magnitude of “g” in SI unit is _______

Answer: 9.8m/s²

Question 4. The magnitude of “g” in the CGS unit is _______

Answer: 981 cm/s²

Question 5. The magnitude of “g” _______is than at the equator.

Answer: Less

Question 6. Speed of a freely falling body _______ at the poles with the increase in the time of fall.

Answer: Increases

Question 7. The distance traversed by a freely falling body _______ with the increase in time of fall.

Answer: Increases

Question 8. If the mass of one object is 2 kilograms, its weight is _______ Newton.

Answer: 19.6

Question 9. Electrons are _______ charged particles

Answer: Negative

Question 10. Like charges _______ each other.

Answer: Repel

Question 11. Unlike charges _______ each other.

Answer: Attract

Question 12. Statcoulomb is the unit of _______

Answer: Charge

Question 13. Keeping the number of charges on two-point- charges fixed, if the distance between them is increased, the electrostatic force will _______

Answer: Decreases

Question 14. When a glass rod is rubbed with a piece of silk it acquires_____charge.

Answer: Positive

Question 15. When an ebonite rod is rubbed with wool, it acquires _______ charge.

Answer: Negative

Question 16. All the positive charges of an atom are contained in the _______

Answer: Nucleus

Question 17. If an atom loses an electron it becomes _______ charged.

Answer: Positively

Question 18. If an atom gains an electron, it becomes _______ charged.

Answer: Negatively

## Chapter 1 Physical Environment Identify as ‘True’ or ‘False’

Question 1. When an object is thrown upwards, it comes down due to gravity.

Answer: True

Question 2. The force of gravitation can never be zero.

Answer: True

Question 3. G is called the Universal gravitational constant.

Answer: True

Question 4. The magnitude of “G” is affected by heat, light, magnetic or electric fields etc.

Answer: True

Question 5. The force of gravity on unit mass is equal to the acceleration dile to gravity.

Answer: True

Question 6. The unit of “G” in the CGS unit is dyne.cm² /g².

Answer: False

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

Answer: False

Question 8. The value of “G” in the SI unit is 6.67/ 108 dyne.cm² / g²

Answer: False

Question 9. Spring balance is used to measure the weight of an object.

Answer: True

Question 10. The average value of “g” in SI unit is 9.8 m/s².

Answer: True

Question 11. In a vacuum, all bodies starting from rest fall with equal rapidity.

Answer: True

Question 12. In absence of any resistance, a heavier object will fall more rapidly than a lighter object.

Answer: False

Question 13. Earth always produces the same acceleration on every object.

Answer: True

Question 14. Electrons are positively charged.

Answer: False

Question 15. Neutrons are negatively charged.

Answer: False

Question 16. Rubbing two objects against each other may produce static electricity.

Answer: True

Question 17. A freely falling body is weightless.

Answer: True

Question 18. If the magnitude of two-point charges is doubled, the electrostatic force will increase by 4 times.

Answer: True

Question 19. Repulsion is a surer test of electrification.

Answer: True

Question 20. Gravitational force is operational between an electron and a proton.

Answer: False

## Chapter 1 Physical Environment Match the Columns

**Question 1.**

Column – A |
Column – B |

A. Law of Universal Gravitation | 1. Galileo |

B. Laws of freely falling bodies | 2. Newton |

C. Naming of different charges as positive and negative | 3. Leaning tower of Pisa |

D. Experiment with falling objects | 4. Franklin |

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

**Question 2.**

Column – A |
Column – B |

A. g | 1. Unit of charge |

B. G | 2. 11.2 km/s |

C. Coulomb | 3. 9.8 m/s^{2} |

D. Escape velocity | 4. 6.67/1011 N.m2/kg2 |

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

**Question 3.**

Column – A |
Column – B |

A. Increase of altitude | 1. G unchanged |

B. Increase in distance between two objects | 2. Force of gravitation |

C. Decrease in distance between two objects | 3. Decrease in gravitation |

D. Increase in mass of two objects | 4. Force of increases |

**Answer:** A-3,B-3,C-2,D-2

**Question 4.**

Column – A |
Column – B |

A. CGS unit of “g” | 1. cm |

B. SI unit of | 2. coulomb |

C. SI unit of charge | 3. N.m^{2}/kg^{2} |

D. CGS unit of distance | 4. cm/s^{2} |

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

**Question 5.**

Column – A |
Column – B |

A. w = | 1. G _{r}2 m^{2} |

B. F = | 2. k q1q2/r^{2} |

C. The electrostatic force of attraction | 3. m.g |

D. g = | 4. w/m |

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