Exploring Forces — Mastery

Q1. Which of the following everyday actions is best described as a 'pull' rather than a 'push'?

• A. Opening a drawer of a table
• B. Pressing an inflated balloon
• C. Kicking a football
• D. Hitting a moving ball with a bat

Q2. In Activity 5.1 the children move a cardboard box by pushing it, pulling it, and lifting it. The chapter uses this activity mainly to establish that

• A. All ways of moving a box require applying a push or a pull
• B. Lifting a box requires no force
• C. A box can be moved without any interaction with another object
• D. Only pulling, not pushing, can move a box

Q3. You push a table with your hand and feel a force on your hand too. As soon as you stop pushing, the force on your hand disappears. This shows that

• A. Forces between two objects continue forever after the first push
• B. Only the hand feels force; the table feels none
• C. The table is pushing the hand only because of friction
• D. Forces exist as long as the two objects interact, and end when the interaction stops

Q4. A goalkeeper stops a fast-moving football with her hands. The force her hands apply on the ball produces which combination of effects?

• A. Changes the colour and the mass of the ball
• B. Decreases the speed of the ball and may also change its shape briefly
• C. Increases the speed and the direction of the ball
• D. Has no effect at all on the ball

Q5. While writing the SI unit of force in a sentence, the chapter prescribes that

• A. The full word 'newton' starts with a small 'n', and its symbol is the capital letter 'N'
• B. Both 'Newton' and 'N' are always written with capital letters
• C. Both the word and the symbol are written with small letters
• D. The unit can be written in any way the writer chooses

Q6. Muscular force inside the human body plays an important role in

• A. Chewing food and pushing it through the alimentary canal during digestion
• B. Producing the electrostatic charge on hair
• C. Generating gravitational force on the body
• D. Producing magnetic force in the brain

Q7. The chapter mentions that an earlier chapter of the same book introduced electromagnets. Electromagnets are devices that

• A. Behave like magnets and so can exert magnetic force
• B. Produce only frictional force
• C. Are made of plastic and exert electrostatic force
• D. Are simply old-fashioned bar magnets

Q8. After Sonali rubs a plastic scale vigorously with polythene, she brings it close to small pieces of paper without touching them. Most likely, she will observe

• A. The paper pieces are pushed away from the scale
• B. The paper pieces burst into flames
• C. Nothing at all happens
• D. The paper pieces get pulled towards the scale and stick to it

Q9. Which row correctly contrasts magnetic / electrostatic forces with gravitational force?

• A. Both can be attractive or repulsive; gravity can be either too
• B. Both can be attractive or repulsive; gravity is always attractive
• C. Both are always attractive; gravity can be repulsive
• D. All three can be both attractive and repulsive

Q10. A spring balance is best described as

• A. A device that uses a stretched spring with a hook to measure weight in newton
• B. A magnet that lifts iron objects and reads their mass
• C. A torch that shines on objects to find their weight
• D. A glass tube filled with liquid to measure temperature

Q11. The spring balance shown in Fig. 5.13 has a range of 0 to 10 N. Which of the following objects can be safely measured on it without damaging the balance?

• A. A bag of rice weighing about 25 N
• B. A school bag weighing about 40 N
• C. A bucket of water weighing about 50 N
• D. A pencil box weighing about 5 N

Q12. From the 'A step further' table comparing Earth, Moon, Mars, Venus and Jupiter for a 1 kg object, we can correctly infer that

• A. Mass changes from planet to planet just like weight does
• B. Weight is the same on every planet but mass is not
• C. Mass stays 1 kg everywhere, while weight differs from planet to planet
• D. Both mass and weight stay exactly the same on every planet

Q13. A shopkeeper says, 'the weight of this wheat bag is 10 kg.' According to the chapter, this statement is

• A. Scientifically correct, because weight is measured in kilograms
• B. Correct only on the Moon, not on the Earth
• C. Wrong because the wheat bag has no weight on Earth
• D. Casual everyday language; scientifically, 10 kg is the mass, not the weight

Q14. Pumice is a rock that can float on water. According to the chapter, it floats because

• A. It contains heavy metals like iron
• B. It is filled with tiny air pockets, making it less dense than water
• C. Volcanic rocks have no weight at all
• D. It is magnetised by the Earth's gravity

Q15. A Class 8 teacher in Rampur wants to introduce 'types of forces' in line with the inquiry-based spirit of the Curiosity textbook. Which of these is the most suitable FIRST step in the lesson?

• A. Dictate definitions of all five forces and ask students to memorise them
• B. Show only a video lecture without any classroom activity
• C. Begin with the Sonali–Ragini cycling story and ask students to list pushes and pulls they have felt in the past week
• D. Give a 30-question test on the chapter before teaching it

Q16. Engineers gave a modern Indian high-speed train its long, tapered nose mainly to

• A. Look modern in advertisements
• B. Reduce muscular force inside the engine
• C. Increase friction so it can brake faster
• D. Reduce friction due to the air around it

Q17. A compass needle pointing North is an example of

• A. Magnetic force between the needle and the Earth
• B. Electrostatic force only
• C. Frictional force
• D. Muscular force from the needle

Q18. A child squeezes a soft rubber ball between her palms; the ball flattens slightly. The force applied has

• A. Made the ball start moving from rest
• B. Changed the direction of motion of the ball
• C. Changed the colour of the ball
• D. Changed the shape of the ball

Q19. Which of the following pairs is correct?

• A. Weight — newton (N); Mass — kilogram (kg)
• B. Weight — newton (N); Mass — newton (N)
• C. Weight — kilogram (kg); Mass — newton (N)
• D. Weight — pascal (Pa); Mass — kilogram (kg)

Q20. Two students argue. Ravi says, 'My mass is 40 kg, my weight on Earth is about 400 N.' Priya says, 'My mass is 40 N and my weight is 40 kg.' Whose statement is scientifically correct, and why?

• A. Priya, because we usually say 'weight' in kg
• B. Both are correct because units do not matter
• C. Neither, because mass and weight cannot be different numbers
• D. Ravi, because mass is in kg and weight (a force) is in newton

Q21. Aman drops a metal coin into a glass of water and the coin sinks. He then places a large wooden block in the same water and the block floats. The best explanation is

• A. For the coin, gravity exceeds buoyant force; for the wooden block, buoyant force is enough to balance gravity
• B. Gravity acts only on the coin, not on the wood
• C. Wood has more mass than the coin
• D. Water is only a liquid to wood, not to the coin

Q22. An object floats steadily on the surface of water (neither sinks nor rises). What does this tell us about the forces acting on it?

• A. Only gravity acts on it
• B. The buoyant force is much larger than its weight
• C. Friction holds it in place
• D. Gravity acting downwards and the buoyant force acting upwards are equal

Q23. In Activity 5.7, after rubbing two balloons with a woollen cloth, the cloth is brought close to one of the rubbed balloons. The most likely observation is

• A. The cloth and the balloon repel each other
• B. Nothing happens between the cloth and the balloon
• C. The cloth and the balloon attract each other
• D. The cloth bursts the balloon

Q24. Many Class 8 students believe, 'if no force is being applied, the object cannot be moving.' For a teacher in Patna, which response best uses this chapter to address the misconception?

• A. Tell them their belief is right; no one moves without a force
• B. Skip the issue and move on to the next chapter
• C. Ask them to memorise the snapshot bullet on friction
• D. Use Activity 5.3 to show a pushed object slides and stops, then explain that the slowing-down is itself caused by friction acting on it

Q25. Before teaching 'magnetic force' as a non-contact force, a constructivist teacher would most likely

• A. Ignore what the children already know and start from a textbook definition
• B. Punish students who give 'wrong' answers about magnets
• C. Test only memorisation of the new definition
• D. First recall and discuss what students learnt about magnets in the Class 6 chapter 'Exploring Magnets'

Q26. True or False: 'Due to friction, the speed of a ball rolling on flat ground increases.'

• A. True — friction is what makes the ball move faster
• B. True — only on smooth ground
• C. Cannot be decided from the chapter
• D. False — friction acts opposite to motion, so it decreases the ball's speed

Q27. When two bar magnets are brought near each other, the chapter recalls that

• A. All combinations of poles repel
• B. All combinations of poles attract
• C. Only the painted surfaces attract
• D. Like poles (N–N or S–S) repel, while unlike poles (N–S) attract

Q28. A teacher uses true-or-false statements (like 'There is no force between two charged objects placed at a small distance apart') as her assessment tool. The MOST important reason for choosing this format for this chapter is that it

• A. Saves time and reduces marking work
• B. Looks attractive in the notebook
• C. Avoids any need for reasoning by students
• D. Surfaces common misconceptions about forces so they can be discussed and corrected

Q29. The 'weight' of an object on the Earth is best defined as

• A. The amount of matter in the object
• B. The size of the object
• C. The force with which the Earth pulls the object towards itself
• D. The density of the object

Q30. A girl in Bhopal throws a small stone vertically up into the air. As the stone goes up, its speed

• A. Goes on increasing because gravity helps it rise
• B. Stays the same throughout the upward journey
• C. Goes on increasing only in the last second
• D. Goes on decreasing until it momentarily comes to rest at the top