🧲 Exploring Forces Class 8 Science Curiosity Chapter 5 Solutions | Keep the Curiosity Alive

Exploring Forces Class 8 Science Curiosity Chapter 5 Keep the curiosity alive

1. Match items in Column A with the items in Column B.

📊 Given:

Column A (Type of force)	Column B (Example)
(i) Muscular force	(a) A cricket ball stopping on its own just before touching the boundary line
(ii) Magnetic force	(b) A child lifting a school bag
(iii) Frictional force	(c) A fruit falling from a tree
(iv) Gravitational force	(d) Balloon rubbed on woollen cloth attracting hair strands
(v) Electrostatic force	(e) A compass needle pointing North

✅ See Answer (with reasoning):

🟢 (a) A cricket ball stopping on its own just before touching the boundary line

➡️ (iii) Frictional force

💡 Explanation:

👉 Grass creates friction 🛑 which opposes motion and slows the ball down

🟢 (b) A child lifting a school bag

➡️ (i) Muscular force

💡 Explanation:

👉 Muscles 💪 apply force to lift the bag against gravity

🟢 (c) A fruit falling from a tree

➡️ (iv) Gravitational force

💡 Explanation:

👉 Earth pulls objects towards itself 🌍 → Gravity

🟢 (d) Balloon rubbed on woollen cloth attracting hair strands

➡️ (v) Electrostatic force

💡 Explanation:

👉 Rubbing creates static charge ⚡ → attracts hair

🟢 (e) A compass needle pointing North

➡️ (ii) Magnetic force

💡 Explanation:

👉 Earth acts like a giant magnet 🧲 → compass aligns North

📊 ✅ Final Matching Table

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 🛑
(iv) Gravitational force	(c) A fruit falling 🍎
(v) Electrostatic force	(d) Balloon attracting hair ⚡

🎯 Quick Revision Trick 🧠

👉 Muscle → Lift 💪

👉 Magnet → Compass 🧲

👉 Friction → Stop 🛑

👉 Gravity → Fall 🌍

👉 Static → Attraction ⚡

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.

👉 See Answer: True ✅

💡 Explanation:

➡️ An object will keep moving at a constant speed 🚶‍♂️ (or stay at rest 🛑) unless a net force acts on it

➡️ To make something speed up or slow down, a push or pull is needed

🔴 (ii) Due to friction, the speed of the ball rolling on a flat ground increases.

👉 See Answer: False ❌

💡 Explanation:

➡️ This is a tricky question 😏

➡️ Friction acts like a brake 🛑

➡️ It always opposes motion, so it reduces speed, not increases

🔴 (iii) There is no force between two charged objects placed at a small distance apart.

👉 See Answer: False ❌

💡 Explanation:

➡️ Charged objects create an electric field ⚡

➡️ When they come close:

✔️ They either attract 🤝

✔️ Or repel 🚫

➡️ This is called Electrostatic Force

⚡ 3. Two balloons rubbed with a woollen cloth are brought near each other. What would happen and why?

👉 See Answer:

🎈 When both balloons are rubbed with the same woollen cloth:

➡️ They get the same type of electric charge ⚡

💡 Think like this:

👉 Same team jersey 👕 = same charge

👉 Same charges → repel each other 🚫

📌 Just like:

🧲 Magnet (North–North / South–South) → repel

➡️ Therefore:

🎈🎈 The two balloons will move apart (repel) due to electrostatic force ⚡

🎯 Quick Revision Trick 🧠

👉 Force changes motion 🔄

👉 Friction slows down 🛑

👉 Same 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.

👉 See Answer:

💡 This is a battle between two forces ⚔️

🔽 1. Gravitational Force (Weight)

➡️ Pulls objects downwards 🌍

🔼 2. Buoyant Force (Upthrust)

➡️ Water pushes objects upwards 💧

🪙 Coin Case:

➡️ Gravity (↓) > Buoyant force (↑)

👉 Coin sinks ⬇️

🪵 Wooden Block Case:

➡️ Buoyant force (↑) ≥ Gravity (↓)

👉 Block floats ⬆️

🎯 Conclusion:

👉 Object floats when upward force balances or exceeds downward force

👉 Object sinks when gravity is stronger

🎾 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) During its upward motion

👉 See Answer:

💡 Two forces act on the ball:

➡️ 🌍 Gravitational Force → Downward ⬇️

➡️ 🌬️ Air Resistance (Friction) → Downward ⬇️

📌 Both forces oppose upward motion → ball slows down

🔽 (ii) During its downward motion

👉 See Answer:

💡 Again two forces act:

➡️ 🌍 Gravitational Force → Downward ⬇️

➡️ 🌬️ Air Resistance → Upward ⬆️

📌 Air resistance now opposes falling motion

⏸️ (iii) At its topmost position

👉 See Answer:

💡 At this instant:

➡️ 🌍 Only Gravitational Force acts downward ⬇️

➡️ 🌬️ Air resistance = zero (because velocity = 0)

📌 Ball stops for a moment before falling

🎯 Quick Revision Trick 🧠

👉 Sink = Gravity > Buoyant 💧

👉 Float = Forces balanced ⚖️

👉 Upward motion → both forces ↓

👉 Downward motion → air ↑, gravity ↓

Question 6, 7 and 8 in Class 8 Curiosity Chapter 5

6. A ball is released from the point P and moves along an inclined plane and then along a horizontal surface as shown in the Fig. 5.16. It comes to stop at the point A on the horizontal surface. Think of a way so that when the ball is released from the same point P, it stops (i) before the point A (ii) after crossing the point A.

Class 8 Science Chapter 5 Image 1

See Answer This is all about controlling friction! The ball stops at point A because of the friction between the ball and the horizontal surface.

(i) To make the ball stop before point A, we need to increase the friction. We could make the horizontal surface rougher, for example, by laying a piece of carpet or sandpaper on it.

(ii) To make the ball stop after crossing point A, we need to decrease the friction. We could make the horizontal surface smoother. Polishing the surface or applying a lubricant like a little bit of oil or talcum powder would reduce friction and allow the ball to travel farther.

7. Why do we sometimes slip on smooth surfaces like ice or polished floors? Explain.

See Answer We can walk because of the friction between the soles of our shoes and the ground. This friction provides the grip we need to push off the ground. Smooth surfaces like ice or a freshly polished floor have very few bumps and irregularities. This means there is very little friction. Without that essential grip, our feet slide easily, causing us to slip.

8. Is any force being applied to an object in a non-uniform motion?

See Answer Yes. Non-uniform motion means the object’s velocity is changing—it’s either speeding up, slowing down, or changing direction. Any change in velocity is called acceleration, and to make an object accelerate, you must apply a net (unbalanced) force. So, if you see an object in non-uniform motion, you can be sure a force is at work.

Class 8 Science Curiosity Chapter 5 Question 9 and 10

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?

See Answer This is a key difference between mass and weight!

The change in weight is caused by the difference in gravity. The Moon is much smaller and has less mass than the Earth, so its gravitational pull is much weaker—about one-sixth as strong. Since weight is just the measure of this gravitational pull, the object’s weight is less on the Moon.

However, the mass of the object does NOT change. Mass is the amount of ‘stuff’ or matter an object is made of. Whether you take a rock to the Moon, to Jupiter, or keep it on Earth, it’s still made of the same amount of stuff. So, its mass remains constant everywhere.

10. Three objects 1, 2, and 3 of the same size and shape but made of different materials are placed in the water. They dip to different depths as shown in 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

Class 8 Science Chapter 5 Image 2

See Answer This is a brilliant puzzle about floating and sinking. Let’s analyze the clues from the picture.

For an object to float, the upward buoyant force must exactly balance its downward weight. The buoyant force is equal to the weight of the water the object pushes aside (displaces).

– Object 1 is floating very high, which means it displaces only a small amount of water. Therefore, it must be the lightest.

– Object 2 is floating lower in the water than object 1. It has to displace more water to stay afloat, which means it must be heavier than object 1. So, W₂ > W₁.

– Object 3 has sunk to the bottom. This means its weight (W₃) is greater than the maximum possible buoyant force the water can provide, even when the object is completely underwater.

From this, we know for certain that the sunken object (3) is the heaviest, and between the two floating objects, object 2 is heavier than object 1.

So the correct order of weights is W₃ > W₂ > W₁.

It appears that none of the multiple-choice options provided in the book match this correct conclusion. This can sometimes happen in textbooks! The most important thing is to understand the scientific principle, which clearly tells us the correct order is W₃ > W₂ > W₁.