Force and Pressure is a chapter in Class 8 science syllabus. This chapter talks about Force and the changes it produces in the body. This chapter also discusses the different types of force and how they act on different bodies. Let’s check NCERT back exercise solutions for Chapter 11, Force and pressure.
Force and Pressure NCERT Solutions for Class 8
Question 1. Give two examples each of the situations in which you push or pull to change the state of motion of objects
In the game of tug of war, people pull each other. This is an example of a situation where we pull each other.
We pull the rope to draw water from a well. In this example the state of the object changes.
Example of Push
When we kick a football then we push the ball to change its state.
Question 2. Give two examples of situations in which applied force causes a change in the shape of an object.
Ans 2: When we knead the dough, then we apply force on it changes the shape of the dough.
When we press stress ball then its shape changes. It changes the shape of the ball
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Question 3: Fill in the blanks in the following statements.
(a) To draw water from a well we have to __________ at the rope.
(b) A charged body __________ an uncharged body towards it.
(c) To move a loaded trolley we have to __________ it.
(d) The north pole of a magnet __________the north pole of another magnet.
Ans 3:
a) pull
b) pulls
c) push
d) repels
Question 4: An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms: muscular, contact, non-contact, gravity, friction, shape, attraction
(a) To stretch the bow, the archer applies a force that causes a change in its __shape____.
(b) The force applied by the archer to stretch the bow is an example of __muscular__ force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a __contact__ force.
(d) While the arrow moves towards its target, the forces acting on it are due to __gravity__ and that due to ____friction__ of air
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Question 5: In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.
(a) Squeezing a piece of lemon between the fingers to extract its juice.
(b) Taking out paste from a toothpaste tube.
(c) A load suspended from a spring while its other end is on a hook fixed to a wall.
(d) An athlete making a high jump to clear the bar at a certain height
Ans5:
(a) Agent is human and object is lemon. We apply muscular force to squeeze the lemon. When the lemon is squeezed its shape changes.
(b) To take out paste from the tube we press it, apply muscular force so agent applying force is us and the object on which the force act is the tube.
(c) A downward force acts on the spring. Suspended load will be the agent here and the object is the spring.
d) In this example, the muscles act as the agent an the object is the athlete itself.
Question 6: A blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering affect the piece of iron?
Ans 6: The hammering changes the shape of the iron object especially when the iron is hot. Repeated hitting of hammer will change the shape of iron object.
Question 7: An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?
Ans 7: When an inflated balloon becomes charged when we rub it against the synthetic cloth. A charged body charges an uncharged body, charge transfer to the balloons and thus it easily gets attracted towards the wall. The electrostatic force is acting in this case.
Question 8:Name the forces acting on a plastic bucket containing water held above ground level in your hand. Discuss why the forces acting on the bucket do not bring a change in its state of motion.
Ans 8: The forces acting on the bucket when we hold it above the round level are:
The gravitational force acting downwards
A muscular force acting in an upward direction
There is no change in the state of motion because both the forces nullify each other’s effect.
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Question 9: A rocket has been fired upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.
Soln:
Two forces will act when the rocket is launched. One force, gravitational force acts downwards while the second force is force of friction applied by air in the earth’s atmosphere. Both the forces act in different directions.
Question 10: When we press the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to
(a) pressure of water.
(b) gravity of the earth.
(c) shape of rubber bulb.
(d) atmospheric pressure
Ans 10)
d) Due to atmospheric pressure, the water tries to move upwards and fills the dropper.
So, these were Force and Pressure NCERT Solutions for chapter no. 11. Stay connected to Careeradvice4u as we keep updating our website with NCERT Solutions for Class 6,7,8,9 and 10. This was Deepak Kumar here. If you want to ask me something you can ask through the comments section below.
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