Force changes the speed of a moving object. Solution: 20. Question 5. (c) muscular force When we push the ball along the level surface, the ball begin to move. 11.7. For example: Falling of apple from tree or falling of any object when we through anything up. Animals make use muscular force to carry out physical tasks. Rod A will go deeper as it has a smaller area of contact, therefore the same force produces more pres¬sure. Question 2. This proves that the pressure in a liquid remains the same in all directions at the same depth. The forces that act when a rocket leaves launching pad are as follows: Some situations have been given in Column 1 of Table 11.2 in which objects are not free to move. _________ is a push or pull acting on an object. Why do deep sea divers wear special suits while diving? Why do astronauts wear special suits in space? Question 14. Answer: The formula for liquid pressure in P=density of the liquid×height×gravitational force. Activity to show liquid exerts pressure at the bottom of container? Why do we observe sparks coming out from a synthetic shirt when we take it off our body ? Match the items given in column I suitably with those given in column II. Push the ball again while it is still moving. Which of the following statements is correct about pressure of water? It can be either between same charges (repulsive, this means they repel each other) or between opposite charges (attractive, this means that they both attract each other). 7. Answer: Question: Why do climbers take oxygen cylinder along while climbing height? Electrostatic force is responsible for this phenomenon. 15. Question 8. (d) pressure, Question 3. Wide strapped bags are used because they are easy to handle. Based on this information fill up the gaps in the following statements using the following terms: (d) do not move the object but may cause a change in its shape. Question 1 How does the pressure of a liquid depends on its depth.Explain? A straw rubbed with paper attracts another straw but repels it if it has also been rubbed with a sheet of paper.The force exerted by a charged body on another charged or uncharged body is known as electrostatic force. Take a large glass jar full of water. Thus, the applied force produces a lower pressure in case of blunt blades, which makes it difficult to cut the cloth. Activity 4 (NCERT Textbook, Page 132) The gas present in the manometer exert pressure therefore mercury level moves down in one limb and rises in other limb. Yes, a force is required to keep the stone moving along a circular path with a constant speed, i.e., the speed does not change. } When the dropper is pressed, the air inside the dropper is driven out. 12. 3. Question 23. Force of gravity is a non-contact force and it acts on a body even though the two are not in contact with each other. (a) electrostatic force Give two examples of each of situations in which you push or pull to change the state of motion of objects? Deep sea divers wear special suits, because the pressure of water increases with depth. Which side will the rope move ? The sparks come out from a synthetic shirt due to the electrostatic charge on it. (a) non-contact This electric charge exerts a pull on the bits of paper. It is a non-contact force. Does the force of gravitation exist between two astronauts in space? The force between magnet and iron is attractive type of force, which means it always attract toward each other and never repel each other. (d) equal in all cases Opening the door is an example of which type of force? Why do sea divers wear specially designed suits? (b) (c) Electrostatic force alone No, Question 6. As a result, nausea kind of disorder is commonly seen and sometimes the blood vessels get burst and mountaineers bleed through the nose (due to increased pressure). })(window, document); Your email address will not be published. (c) A load suspended from a spring while its other end is on a hook fixed to a wall. Can weight be taken as a measure of force ? (ii) Pull: We draw water from a well by pulling the rope. Make sure that its top surface is levelled. Why does a sharp knife cut objects more effectively than a blunt knife? (b) Give one example of gravitational force. We move a wooden box by pushing. 9. Last Updated on May 29, 2019 By Mrs Shilpi Nagpal 21 Comments. In case of rod B the same force produces less pressure. Make a 50 cm × 50 cm bed of dry sand about 10 cm in thickness. A brick is kept in three different ways on a table as shown in given figure. When we press the foam, its shape is changed. State the effect of the force in each case. Then to measure gas pressure, we need to connect one side of the manometer with gas supply. 3. Discuss why the forces acting on the bucket do not bring a change in its state of motion? It consists of u-shaped glass tube which contains mercury. What force might be responsible for the attraction between the balloon and the wall? (a) non-contact forces Answer: A heavy truck is fitted with six to eight wheels because increased area reduces the pressure on wheels so they do not burst or damage on the road. Pour some more water in the bottle. Blood pressure is little greater than atmospheric pressure. What is force? It extends up to many kilometers. No, the force can also act from a distance. Fill in the Blanks Drill four holes all around near the bottom of the bottle. (b) muscular force 9. This means that if pressure increases area decreases. It is also a contact force. For example: For brushing the teeth, we need to squeeze the toothpaste and apply it on our brush. Force: (i) Force is a push or a pull. Question: Activity to show liquid exerts pressure at the bottom of container? Also take a piece of thin sheet of a good quality rubber, say, a rubber balloon. 11.11. Pressure is force per unit area. (b) Question 3. 1. pull (d) Electrostatic force, Question 21. 7. Answer: (c) Force of friction (c) pressure False It is the force exerted by the muscles. if(k.className == "adPushupAds" && k.getAttribute("data-push") != "1") { Therefore, we feel warm. Pressure = force / area. Since the pressure of liquid increases with the increasing depth of sea. Can you see any relation between the amount of the bulge in the rubber sheet and the height of the water column in the pipe? Note whether the bottle in which water is poured gets filled first or all the bottles get filled up simultaneously. It is the force exerted by earth’s gravity on all objects. Can you move it? True Now pour water in any one of the bottles. Give reasons for the following : Question 5. Foundations of high-rise buildings are kept________, Iron nails can be separated from husk by using_________. ___________ and ___________ forces are the two kinds of forces. There should be atleast two objects for a force to come into play. Yes, the rubber tube bulge out and the bulging increases with the amount of water in the bottle. Like we cannot push or pull the book kept on a table without touching it. Place the longer side of one of the magnets over three round shaped pencils or wooden rollers as shown in Fig. (b) contact When we place our palm in front of the moving ball, decreases its speed. All points at the same level in a liquid are at the same pressure. Question 9. Question 2. (c) The type of force responsible for a change in the state of motion of the arrow is an example of a ______ force. Muscular force is also known as contact force. Do you think why it is easier to hammer a nail into the wall. The force acting on the bucket do not bring a change in state of motion because they are acting in opposite directions with equal magnitudes. (g) What is meant by muscular force ? Two boys A and B are applying force on a block. 5. push, pull Jake a rubber ball and place it on a level surface such as a tabletop or a concrete floor. What is the name of the instrument used to measure atmospheric pressure? Pressing a rubber ball with the hand changes its shape. (c) difference between the two unbalanced forces and is in the direction of the larger force. distance the ball comes to rest. 10. (b) decreases with depth The force of attraction exerted by the earth on all objects is called the force of gravitation. Question 2. (d) Magnitude, Question 4. (d), Question 3. (a) To draw water from a well we have to ______ at the rope. Answer: Two rods: A and B, having same weight and equal length have different thickness. When the force is applied opposite to the motion of the object, then either the speed decreases or the direction changes. (c) Net force on the block is towards B. Question 3. Question 17. Negative charge on the balloon attracts positive charge on water molecules. Force of gravity is a non-contact force. In a tug of war, side A applies 10 newton force and side B applies 8 newton force. Answer: (c) Magnetic force, i.e., the force exerted by a magnet on another magnet or a piece of iron. (b), Question 6. It is because we apply a greater amount of force into a very small area of the screw head. Both the persons are applying forces from opposite direction with equal magnitudes. Shreya is dutiful, friendly with scientific aptitude. Answer: Gas pressure can be measured by using an instrument called Manometer.