In this post we will see science class 8th chapter 11 solution.
You can check the Complete Science Solution here – NCERT Class 8th Science Solutions – Complete Solution List
Chapter 11 Solutions
1. Give two example each of situation in which you push or pull to change the state of motion of object.
Answer -Two examples of push force are as follow –
(i) A heavy box at rest is pushed to move it from one room to another. This change the state of motion of the box.
(ii) A player pushes a football using his foot. This change the state of motion of the ball.
Two examples of pull force are as follows:
(i) Rope is pulled to draw water from a well. This changes the state of motion of the water bucket.
(ii) A drawer is to it. This change the state of motion of the drawer.
2. Give two examples of situation in which applied force causes a change in the shape of an object.
Answer – Two examples of force that cause in the shape of an object are as follow –
(i) Squeezing of a plastic bottle changes the space of the bottle.
(ii) Deformation of clay be pressing it between the hands.
3. Fill in the blankes in the following statements.
(a) To draw water from a well we have to ___________ at a rope.
(b) A charged body __________ an uncharged body toward it.
(c) To move a loaded trolley we have to _____________ it.
(d) The north pole of a magnet ____________ the north pole of another magnet.
Answer – (a) To draw water from a well we have to__pull_ at a rope.
(b) A charged body __attracts__ an uncharged body towards it.
(c) To move a loaded trolley we have to either push or pull_ it.
(d) The north pole of a magnet __repels__ the north pole of another magnet
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. _______.
(b) The force applied by the archer to stretch the bow is an example of ________ force.
(c) The type of a force responsible for a change in the state of motion of the arrow is an example of _______ force.
(d) While the arrow moves toward its target, the force acting on ot are due to _______and that due to ________ of air.
Answer – (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 a force responsible for a change in the state of motion of the arrow is an example of __contact__ force.
(d) While the arrow moves toward its target, the force acting on it are due to __gravity__ and that due to __friction__ of air.
5. In the following situation 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 toothbrush 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.
Answer – (a) In squeezing a piece of lemon, we make use of muscular force to extract its juice. This muscular force acts on the lemon. As the result, the shape of the lemon gets changed.
(b) We use our muscular force to take out paste from a toothpaste tube. The muscular force acts on the toothpaste tube. As a result, the spring gets stretched. Hence, its shape gets charged.
(c) Here, the suspended load exets a force on the spring and pushes the spring downward. As a result, the spring get stretched. Hence, its shape gets changed.
(d) An athlete pushes the ground with his feet. His feet exert a muscular force on the ground. This allows him to jump over the bar. As a result, his state of motion gets changed.
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?
Answer – When a blacksmith hammers a hot piece of iron, he uses his muscular force. This muscular force change the shape of the iron so that it can be given a desired shape.
7. An inflated baloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the baloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall ?
Answer – On rubbing an inflated boloon with a piece of synthetic cloth, it becomes charged. A charged body attracts an uncharged body. When this charged baloon is pressed against a wall, it sticks to the wall. The force acting between the charged baloon and the wall is the electrostatic force.
8. Name the force 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.
Answer – We make use of muscular force to hold a bucket of water above the ground. This muscular force acts against the force of gravity that pulls the the bucket toward the ground. The two forces are equal in magnitude but opposite in direction. Therefore, the net force on the bucket is zero. Hence, there is no change in its state of motion.
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.
Answer – The two forces acting on the rocket are the force of gravity, which pulls the rocket towards the ground, and the force of friction due to earth’s atmosphere. Which oppose its motion.
10. When we press the bulb of 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 to the earth.
(c) Shape of rubber bulb.
(d) Atmospheric pressure.
Answer – (d) The rise of water in the dropper is due to atmospheric pressure. The rise of water in a dropper is due to atmospheric pressure. When all the air escapes from the nozzle, the atmospheric pressure, which is acting on the water, forces the water to fill the nozzle of the dropper.
You can check the Complete Science Solution here – NCERT Class 8th Science Solutions – Complete Solution List
You can see other posts here.
- Class 8th NCERT Science Solution Chapter 7 – Conversation of Plant and Animal
- Class 8th NCERT Science Solutions Chapter 8 – Cell Structure and Function
- Class 8th NCERT Science Solution Chapter 9 – Reproduction in Animals
- Class 8th NCERT Science Solution Chapter 10 – Reaching the age of adolescence
Tags – NCERT solution of class 8th, Solution of science class 8th chapter 11, Chapter 11 class 8th science solution, NCERT solution of science for class 8th, Class 8th science solution, Science solution for class 8th chapter 11.
