Class 8 Science Chapter 8 Force And Pressure Long Answer Type Questions And Answers
Question 1. Two groups of students are playing tug-of-war.
1. Choose the correct direction of force applied by Group Land Group 2.
Answer: 4.
2. Group1 is pulling with a 250 N force, and Group 2 is pulling with a 300 N force. What would be the likely position of the two groups after a minute of pulling?
Answer: 1. Net 50n Force Demonstration Winning Team Movement
Read And Learn More CBSE Class 8 Science Long Answer Questions
Question 2. Rishi drops a metal block from the same height onto different wooden blocks of the same mass but different contact areas. The teacher was also watching this activity. He asked Rish some questions to Rish, which are listed below.
Explain the relationship between the contact area of the wooden block and how deeply the wooden block would sink into the soft ground.
A force of 100 N is applied on an area of 4 m 2. Calculate the pressure applied to the area.
The contact area of one of the wooden blocks is 9 cm2. Calculate the force acting on it if the pressure is 900 Pa.
Question 3. Four students wanted to find out who could kick a football the strongest. Each student kicked the football. The table shows the distance the football travelled in the air before hitting the ground.
1. Which student kicked the ball with the greatest force?
- Student 1
- Student 2
- Student 3
- Student 4
2. Which of these factors must remain the same when each student kicks the football? Choose ‘Yes’ or ‘No’ for the correct response.
Shade the columns in the graph to correctly show the data in the table.
Answer:
As pressure is equal to force divided by area, hence as the contact area of the wooden block increases, the depth to which block would sink into the soft ground decreases.
⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}\)
Force = 100 N, Area = 4 m2
⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}=\frac{100}{4}=25Pa\)
The relation between pressure and force is
⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}\)
Force = Pressure X Area
= (900) (0.0009) ( v 9 cm 2 = 0.0009 m 2 )
= 0.81 N
Question 3. It is much easier to burst an inflated balloon with a needle than with a finger. Explain.
Answer:
Because the needle tip has a very small area of cross-section in comparison to that of our finger, and we know that pressure exerted by a force is inversely proportional to the area where it has been applied, the pressure exerted will be more by the needle tip than the finger.