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CLASS VIII SCIENCE, REVISION WORSHEET, FORCE AND PRESSURE, Q1. What is force? Write its S.I unit. What are the effects of force?, Q2. Name the type of force acting in the following conditions:, a., b., c., d., e., , To pick your school bag., To collect scrap iron from garbage using magnet., Flying of seeds away from each other in plastic bag when gently rubbed, Downward motion of an object even when it is thrown upwards., Ball rolling on the ground slows down after travelling some distance and finally, comes to rest., , Q3. Differentiate between: Contact and non-contact forces, Q4. What is Pressure? Write its formula and S.I unit., Q5. How would pressure change if, a. Area is doubled keeping force constant., b. Force is doubled keeping area constant., c. Area is halved keeping force constant., Q6. Give reason for the following:, a. High- rise buildings are provided with wide foundations., b. Potters place a round piece of cloth on their heads when they have to carry heavy, loads., c. Athletes wear specially designed shoes with spikes on the soles., d. Tools meant for cutting always have sharp edges., e. Mountaineers suffer from nose bleeding at high altitudes., Q7. Define atmospheric pressure. Why do we not feel the atmospheric pressure?, Q8. If you pierce many holes down the side of a plastic bottle having water, then through, which hole the jet of water will travel farthest and why?, Q9. How do rubber suckers stick to the wall?, Q10. How much pressure is exerted by an elephant on the ground, if its weight is 50,000N, and area under its foot is 0.1 m2?, Q11. A force of 400N exerts pressure of 20N/m2. What is the area on which pressure acts?

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Q12. Fill in the blanks(i), (ii), (iii), (iv), (v), , The strength of a force is expressed by its ________., Forces applied on an object in the _________ direction add to one another., If the two forces act in the opposite directions on an object, the net force, acting on it is the ______________the two forces., Pressure exerted by water at the bottom of the container depends on the, __________ of its column., Liquids exert _______ pressure at the same depth.