Exploring Forces solutions Class 8 Curiosity NCERT
30 October
Exploring Forces Solutions Class 8 Curiosity
🌟 Welcome to the World of Forces!
Have you ever wondered why it's tough to push a heavy box or why your feet slip on a wet floor? These everyday experiences are all linked to one powerful concept — Force! In this exciting chapter, "Exploring Forces", you will discover what force is, how it affects motion, and the fascinating types of forces all around us — from gravity that pulls objects down, to friction that resists motion.
Let's dive deep into the in-text and exercise questions of this chapter and uncover the mysteries of how the universe moves and interacts!
Class 8 – Curiosity
In-Text Questions:
1. Why does it feel harder to pedal a bicycle when going uphill than on flat ground?
It feels harder to pedal uphill because you are working against gravity. You have to apply more force to overcome the downward pull of gravity while going up, which requires more energy compared to pedaling on flat ground.
2. Why is it easier to slip on a wet surface?
A wet surface reduces friction between your feet and the ground. Friction provides grip, and when it’s low, it becomes easier to slip.
3. Why do we feel ‘light’ or like we are ‘floating’ just after our swing reaches its highest point and begins to come down?
At the highest point, the swing momentarily stops before changing direction. During this brief moment, there’s no upward force from the swing seat, and you feel weightless because of free fall — similar to floating.
4. What is a Force?
A force is an agent, which is a push or a pull on an object that can change its state of motion or shape or direction.
5. What can a Force do to the bodies on which it is applied?
A force can:
- Move a stationary object
- Stop a moving object
- Change the speed or direction of an object
- Change the shape of an object
6. Are Forces an Interaction Between Two or More Objects?
Yes, forces always involve an interaction between at least two objects — one applying the force and the other receiving it.
7. What are the Different Types of Forces?
The main types of forces are:
- Contact forces – e.g., muscular force, friction, normal reaction, tension, etc
- Non-contact forces – e.g., gravitational force, magnetic force, electrostatic force
8. Does this mean that the force of friction will be greater if the surfaces are rough?
Yes, rough surfaces have more irregularities that interlock with each other, increasing friction. So, the force of friction is greater on rough surfaces.
9. Is it essential for an object applying force on another object to always be in contact with it?
No, some forces like gravitational force, magnetic force, and electrostatic force can act from a distance without direct contact.
10. Does it mean that there are two kinds of electrical charges?
Yes, there are two types of electrical charges — positive and negative. Like charges repel each other, while unlike charges attract.
11. Why do all the objects fall towards the Earth? Is there any force which acts on them? What exerts this force?
Yes, the gravitational force of the Earth pulls all objects toward it. This force is exerted by the Earth and acts on all objects with mass.
12. Does the Earth pull every object with equal force?
No, the Earth pulls objects with a force that depends on their mass. Heavier objects experience a greater gravitational pull than lighter ones.
13. What is the difference between weight and mass?
- Mass is the amount of matter in a body. It is constant and measured in kilograms (kg).
- Weight is the force of gravity acting on the body. It changes with location and is measured in newtons (N).
14. If we place some objects on water, some of them float, while others fall to the bottom. The gravitational force of the Earth is acting on all objects, then why don’t all objects fall to the bottom?
Objects float or sink based on their density. If an object is less dense than water, it floats. If it is denser, it sinks — despite gravity acting on all.
Exercise Questions:
1. Match items in Column A with the items in Column B.
| Column A (Type of force) | Column B (Example) |
|---|---|
| (i) Muscular force | (b) A child lifting a school bag |
| (ii) Magnetic force | (e) A compass needle pointing North |
| (iii) Frictional force | (a) A cricket ball stopping on its own |
| (iv) Gravitational force | (c) A fruit falling from a tree |
| (v) Electrostatic force | (d) Balloon attracting hair strands |
2. State whether the following statements are True or False:
- (i) A force is always required to change the speed of motion of an object. — True
- (ii) Due to friction, the speed of the ball rolling on a flat ground increases. — False
- (iii) There is no force between two charged objects placed at a small distance apart. — False
3. Two balloons rubbed with a woollen cloth are brought near each other. What would happen and why?
Both balloons will repel each other. Rubbing them with wool gives them the same type of electric charge, and like charges repel.
4. When you drop a coin in a glass of water, it sinks, but when you place a bigger wooden block in water, it floats. Explain.
The coin sinks because it is denser than water and the upward force (buoyancy) is less than its weight. The wooden block, though larger, is less dense than water, so the upward buoyant force is greater than its weight, and it floats.
5. If a ball is thrown upwards, it slows down, stops momentarily, and then falls back to the ground. Name the forces acting on the ball and specify their directions:
- (i) Upward motion: Gravity acts downward, opposing the motion.
- (ii) Downward motion: Gravity acts downward, aiding the motion.
- (iii) At topmost position: Velocity is zero; force of gravity still acts downward.
6. A ball is released from point P and comes to stop at point A. Think of a way so that it stops:
- (i) Before point A: Use a rougher surface or apply brakes/friction earlier.
- (ii) After point A: Make the horizontal surface smoother or reduce friction.
7. Why do we sometimes slip on smooth surfaces like ice or polished floors? Explain.
Smooth or polished surfaces offer less friction. Without enough friction, our feet can't grip the surface properly, making us slip.
8. Is any force being applied to an object in a non-uniform motion?
Yes. A force is required to change the speed or direction of an object. Non-uniform motion means speed or direction is changing, hence a force must be acting.
9. The weight of an object on the Moon becomes one-sixth of its weight on the Earth. What causes this change? Does the mass of the object also become one-sixth of its mass on the Earth?
Weight changes because gravity on the Moon is weaker — about one-sixth of Earth’s gravity. Mass remains constant everywhere. So, only weight changes, not mass.
10. Three objects 1, 2, and 3 of the same size and shape but made of different materials are placed in water. They dip to different depths as shown in the figure (Fig. 5.17).
If the weights of the three objects 1, 2, and 3 are w₁, w₂, and w₃ respectively, then:
- (i) w₁ = w₂ = w₃
- (ii) w₁ > w₂ > w₃
- (iii) w₂ > w₃ > w₁
- (iv) w₃ > w₁ > w₂
✅ Answer:
Correct Option: (ii) w₁ > w₂ > w₃
The more an object sinks in water, the more it weighs — assuming all objects have the same shape and size (volume). Object 1 is submerged the most, so it is the heaviest. Object 3 floats the highest, so it is the lightest.
Hence, w₁ > w₂ > w₃.
🌟 Keep Exploring, Keep Growing!
Science is not just about reading facts — it’s about asking questions, exploring the world around you, and finding answers through curiosity and logic. Every time you understand a new concept, you're not just learning — you're growing as a thinker.
So never stop wondering, never stop questioning, and always stay curious! Because the more you explore, the more exciting the journey becomes. 💡🚀
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