Class 8 Science

NCERT Solutions For Class 8 Science Chapter 8 Force And Pressure LAQs

Question 1. In walking, the pressure on the ground is greater than that in standing on the ground. Explain this statement.

Answer: When a person is walking on the ground, at one time, one foot is only on the ground. Therefore, the entire weight of a man falls on a smaller area of the ground, which results in a large pressure on the ground. While in another case, if the man is standing on the ground, then both his feet are on the ground. It causes the force of weight of a man to fall on a larger area of ground and results in less pressure on the ground.

NCERT Solutions for Class 8 Science Force and Pressure

Question 2. Two women are of the same weight. One wears sandals with pointed heels while the other wears sandals with flat soles. Which one would feel more comfortable while walking on a sandy beach? Give reasons for your answer.

Answer:

While walking on a sandy surface, one needs footwear larger area so that the pressure exerted on the ground is minimal. So, in this case, the woman having the sandals with pointed heels will be less comfortable while walking, while the other woman wears sandals with flat soles, feels more comfortable while walking on a sandy beach.

Question 3. It is difficult to cut cloth using a pair of scissors with blunt blades. Explain.
Answer:

It is difficult to cut cloth using a pair of scissors with blunt blades because blunt blades have more area, and due to this, the applied force produces very little pressure. As we know that pressure is inversely proportional to the area of cross-section, so it is difficult to cut cloth with blunt blades

⇒ (\(p=\frac{F}{A}\))

NCERT Solutions for Force and Pressure Chapter 8

Question 4. Observe the vessels A, B, C, and D as shown in the figure carefully.

The volume of water taken in each vessel is as shown. Arrange them in the order of decreasing pressure at the base of each vessel. Explain.
Answer:

1. Pressure at depth due to the liquid column depends upon
2. Gravitational acceleration
3. Density of liquid
4. Height of liquid.

And in this case, gravitational acceleration and density are the same, so the only thing that can change pressure is height.

NCERT Class 8 Science Chapter 8 Force and Pressure Solutions

So, the order of pressure exerted by the fluids A, B, C, and D at the base is given by

PD> PB > PA > PC

Question 5. An archer shoots an arrow in the air horizontally. However, after moving some distance, the arrow falls to the ground. Name the initial force that sets the arrow in motion. Explain why the arrow ultimately falls.
Answer:

The archer shoots an arrow by applying muscular force by stretching the string of the bow. When the string is released, it regains its original position that provides the initial force to set the arrow in motion horizontally. The force of gravity acts on the arrow in the downward direction, and hence the arrow ultimately falls to the ground.

NCERT Class 8 Science Chapter 1 Crop Management Multiple Choice Questions

Question 1. The system of Irrigation, where water is supplied drop by drop near the roots of plants, is called

1. Pulley system
2. Drip system
3. Sprinkler system
4. Lever system

Answer: drip system

Question 2. Weeds are the

1. Main crop plants
2. Insects and pets
3. Unwanted plants growing along the crop
4. Chemical substance

Answer: Unwanted plants along the crop

NCERT Class 8 Science Chapter 1 Crop Management MCQs

Question 3. Given below are statements about the harmful effects of wood on crop plants.

1. They interfere with harvesting.
2. They help crop plants grow healthy.
3. They compete with crop plants for water, nutrients, space, and light.
4. They affect the plant growth

Answer: They interfere with harvesting.

NCERT Class 8 Science Chapter 1 Crop Production MCQs With Answers

Choose the correct combination of statements

1. (1),  (3), and (4)
2. Only (3)
3. (3) and (4)
4. (1), (2), and (4)

Answer: 1. (1),  (3), and (4)

Question 4. 2,4-D is a

1. Pesticide
2. Insecticide
3. Fungicide
4. Weedlcide

Answer: Weedicide

Question 5. The term used for the process of separation of grains from chaff is

1. Sieving
2. Winnowing
3. Threshing
4. Hand Picking

Answer: Threshing

NCERT Solutions for Crop Management MCQs Chapter 1

Question 6. Why are the grains dried in the Sun before storing them?

1. To keep the grains warm
2. To increase the size of the grains
3. To prepare the grains for germination
4. To reduce the moisture content of the grains

Answer: To reduce the moisture content of the grains

Question 7. How can food Items like milk, eggs, and meat be produced on a large scale?

1. By doing animal husbandry
2. By performing plant harvesting
3. By providing food to the animals
4. By storing grains in big godowns

Answer: By doing animal husbandry

CBSE Class 8 Science Chapter 1 Multiple Choice Questions

Question 8. Which of the following is not a Rabl crop?

1. Linseed
2. Pea
3. Gram
4. Groundnut

Answer: 4 Groundnut

Question 9. What tool should the farmer select to safeguard seeds from animal consumption while sowing?

1. Seed drill as it coats a chemical above the seeds
2. Traditional tool, as many seeds are sewn together
3. Seed drill, as it covers the seeds with soil after sowing
4. A conventional tool as seeds, passes through a funnel-shaped cube

Answer: 3 Seed drill as it covers the seeds with soil after sowing

Class 8 Science Chapter 1 Crop Management MCQs

Question 10. Which of the following statements is incorrect?

1. Freshly harvested grains must be dried before storing.
2. Organic fertiliser has a balance of all plant nutrients
3. Weeding is the process of growing weeds
4. The drip irrigation system is suitable for fruit plants

Answer: 3 Weeding is the process of growing weeds

Question 11. What advantages can the farmer expect from transitioning to using manure after a prolonged period of using fertilisers on his land?

1. It will improve the texture and water retention capacity of the soil.
2. It will decrease the number of earthworms in the soil
3. It will make the soil more compact to hold more water in the roots
4. It will increase particular chemicals in the soil to increase the yield

Answer: 1. It will improve the texture and water retention capacity of soil.

Crop Management MCQs Class 8 NCERT

Question 12. Which of the following is not a traditional method of irrigation?

1. Moat
2. Chain pump
3. Sprinkler system
4. Dhekli

Answer: 3. Sprinkler system