Question Bank — Exploring Forces

Section A — MCQs (10 questions, 1 mark each)

1. Which of the following is an example of a contact force?
   (a) Magnetic force
   (b) Electrostatic force
   (c) Muscular force
   (d) Gravitational force

2. Friction always acts:
   (a) In the direction of motion
   (b) Opposite to the direction of motion
   (c) Perpendicular to the surface
   (d) Only when objects are at rest

3. Assertion (A): Two similarly charged balloons repel each other.
   Reason (R): Like charges repel and unlike charges attract.
   (a) Both A and R are true and R is the correct explanation of A.
   (b) Both A and R are true but R is not the correct explanation of A.
   (c) A is true but R is false.
   (d) A is false but R is true.

4. The SI unit of force is:
   (a) Joule
   (b) Newton
   (c) Pascal
   (d) Watt

5. Which force is responsible for a fruit falling from a tree?
   (a) Magnetic force
   (b) Electrostatic force
   (c) Gravitational force
   (d) Muscular force

6. Assertion (A): A ball rolling on a rough surface stops after some time.
   Reason (R): Friction acts in a direction opposite to the motion of the ball.
   (a) Both A and R are true and R is the correct explanation of A.
   (b) Both A and R are true but R is not the correct explanation of A.
   (c) A is true but R is false.
   (d) A is false but R is true.

7. The force exerted by a charged body on another body without physical contact is called:
   (a) Magnetic force
   (b) Electrostatic force
   (c) Muscular force
   (d) Frictional force

8. When an object is placed in water, the upward force exerted by the liquid is known as:
   (a) Gravitational force
   (b) Upthrust or buoyant force
   (c) Magnetic force
   (d) Electrostatic force

9. Which of the following is a non-contact force?
   (a) Friction
   (b) Muscular force
   (c) Magnetic force
   (d) Force applied while pushing a box

10. The weight of an object is measured in:
    (a) Kilograms only
    (b) Newtons
    (c) Grams only
    (d) Metres

Section B — Very Short Answer (6 questions, 2 marks each)

1. Define force. Give one example of a push and one of a pull from daily life.
2. State two effects of force on an object.
3. What is muscular force? Name one activity where muscular force is used by animals.
4. Why does friction arise between two surfaces?
5. Differentiate between contact and non-contact forces with one example of each.
6. What is the difference between mass and weight of an object?

Section C — Short Answer (5 questions, 3 marks each)

1. Explain with an example how force can change the direction of motion of an object.
2. Draw a labelled diagram of two ring magnets arranged on a stick such that the upper magnet floats. Label the poles and state what this shows about magnetic force.
3. Why do objects moving through air or water experience friction? How is this used in designing vehicles?
4. Describe an activity to show that like charges repel and unlike charges attract.
5. What is upthrust? Explain why some objects float while others sink in water.

Section D — Long Answer (3 questions, 5 marks each)

1. What is gravitational force? Describe an activity using a spring balance to show that the Earth pulls different objects with different forces. Also explain the difference between mass and weight. (Include a labelled diagram of a spring balance with an object suspended from it.)

2. Explain the cause and nature of frictional force. How does the nature of surfaces affect friction? Describe an activity to show that friction depends on the type of surface in contact.

3. Describe the different types of non-contact forces with one example of each. How is gravitational force different from magnetic and electrostatic forces?

Section E — Case/Source-Based (2 questions, 4 marks each)

Passage 1:

Sonali and Ragini were cycling on a windy day. While going uphill they had to pedal harder. On the way down the slope their bicycles moved fast even without pedalling. They also used muscular force to press the bells and turn the handles.

(i) Identify two situations from the passage where force changes the speed of the bicycles. (1)
(ii) Which type of force is used when they press the bicycle bells? (1)
(iii) Name the force that pulls the bicycles downhill. (1)
(iv) Why did they have to pedal harder while going uphill? (1)

Passage 2:

When two balloons are rubbed with a woollen cloth and brought near each other, they move apart. When the woollen cloth is brought near one balloon, they move towards each other.

(i) What kind of force is acting between the two balloons? (1)
(ii) Why do the balloons move apart? (1)
(iii) Why does a balloon move towards the woollen cloth? (1)
(iv) State the rule about like and unlike charges based on this observation. (1)

Section F — HOTS and Application (4 questions, 3 marks each)

1. Predict-and-justify: What would happen if the force of friction suddenly became zero on a road? Justify your answer with reasons.
2. Analyse an anomalous observation: In an experiment, a student observes that a ball rolling on a smooth glass surface travels much farther than on a wooden table before stopping. Analyse this observation and explain the reason.
3. Apply to an unfamiliar situation: A person finds it easier to walk on a muddy road wearing shoes with deep grooves than on a wet polished floor with smooth soles. Apply the concept of friction to explain this real-life situation.
4. Compare two situations: Compare the motion of a ball thrown vertically upwards on Earth with the same situation if gravitational force were absent. Justify which outcome differs and why.