NCERT Solutions For Class 8 Science Chapter 8 Force And Pressure SAQs
Question 1. The figure shows a magnet at the top of a ramp and paper clips at the base of the ramp. He observed that the paper clip moved up the ramp and attached to the magnet. What forces were acting on the paper clip as it moved up the ramp?
Answer:
The paper clip moved up the ramp because it was attracted to the magnet, therefore, there was a magnetic force acting on it.
Gravitational and frictional forces also continue to act on the paper clip as it moves up the ramp.
NCERT Solutions for Force and Pressure SAQs Class 8
Question 2. A chapati maker is a machine that converts balls of dough into chapatis. What effect of force comes into play in this process?
Answer:
The force per unit area is called pressure, which works on the chapatis. This is the pressure that works on the dough balls and makes them chapatis with the help of a machine.
Question 3. Wooden or concrete sleepers are kept below the railway line. Explain why?
Answer:
Since the area on which the weight of the train acts increases which resulting in a decrease in the pressure on the ground which the train moves easily on the railway line without any risk of an accident. So, this is the reason for keeping the wooden or concrete below the railway line.
NCERT Solutions for Class 8 Science Force and Pressure SAQs
Question 4. Determine the pressure when a force of 200 N acts on the area
- 20 m² and
- 8m²
Answer:
⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}\)
Given, F = 200N
For area, A=20m2
⇒ \(p=\frac{200}{20}=10 \mathrm{~N} / \mathrm{m}^2 \text { or } 10 \mathrm{~Pa}\)
⇒ \(p=\frac{200}{8}=25 \mathrm{~N} / \mathrm{m}^2 \text { or } 25 \mathrm{~Pa}\)
Question 5. Raman was very curious to know how the porters carry a heavy load on their heads easily. Suddenly, he asked his teacher, and the teacher told him that by reducing the pressure on the head, the porters can carry a heavy load.
- Explain how the porters carry heavy loads easily.
- Mention your views about Raman.
Answer:
The porters usually cover their heads with thick, round cloths before carrying the load. This increases the area ofcontact, therefore reducing pressure on the head. So, the porters carry a heavy load easily.
According to me, Raman is very curious to know about science.
NCERT Solutions for Force and Pressure Chapter 8 SAQs
Question 6. Two rods of the same weight and equal length have different thicknesses. They are held vertically on the surface of the sand as shown in the figure. Which one of them will sink more? Why?
Answer:
As we know, pressure exerted by the body is inversely proportional to the area where force is applied. So, the thinner rod, i.e., rod B, will sink more because it has less area of cross-section in contact with the surface, hence it will exert more pressure on the sand than rod A.
Question 7. What type of force is involved in each of the given conditions? Put a tick mark for the response in terms of push or pull.
Answer:
Force and Pressure Class 8 NCERT SAQs
Question 8. If the area of my head were 15 cm x 15 cm, how much force would air exert on my head?
Answer:
We know that. 1 atmospheric pressure =10 s N/m: = 10N/cm2
⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}\)
Force = Pressure x Area =10x(15xl5) =2250 N.
Question 9. Give two examples each of situations in which you push or pull to change the state of motion of objects.
Answer:
The two examples are as follows:
- We push the door open.
- We pull a drawer to open it.
Force and Pressure SAQs NCERT Solutions Class 8
Question 10. Give two examples of situations in which applied force causes a change in the shape of an object.
Answer: The two examples are as follows:
- Spring: When we compress or stretch the spring, it changes its shape.
- Foam: When we compress the foam or sponge, it changes its shape.