{"id":22261,"date":"2024-02-21T17:53:16","date_gmt":"2024-02-21T12:23:16","guid":{"rendered":"https:\/\/icsesolutions.com\/?p=22261"},"modified":"2024-02-22T09:45:19","modified_gmt":"2024-02-22T04:15:19","slug":"selina-concise-physics-class-6-icse-solutions-simple-machines","status":"publish","type":"post","link":"https:\/\/icsesolutions.com\/selina-concise-physics-class-6-icse-solutions-simple-machines\/","title":{"rendered":"Selina Concise Physics Class 6 ICSE Solutions – Simple Machines"},"content":{"rendered":"
ICSE Solutions<\/a>Selina ICSE Solutions<\/a>ML Aggarwal Solutions<\/a><\/p>\n APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 6 Physics. You can download the Selina Concise Physics ICSE Solutions for Class 6 with Free PDF download option. Selina Publishers Concise Physics for Class 6 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.<\/p>\n Selina Class 6 Physics ICSE Solutions<\/a>Chemistry<\/a>Biology<\/a>Maths<\/a>Geography<\/a>History & Civics<\/a><\/p>\n Selina Concise ICSE Solutions for Class 6 Physics Chapter 4 Simple Machines<\/strong><\/p>\n Test yourself<\/strong><\/span><\/p>\n A. Objective Questions<\/strong><\/span><\/p>\n 1. State whether the following statements are True or False.<\/strong><\/p>\n (a)<\/strong> A boy does work while pushing a wall. (b)<\/strong> A machine performs work by itself. (c)<\/strong> In an ideal machine, work done on load is equal to the work done by effort. (d)<\/strong> All levers are force multipliers. (e)<\/strong> A pulley changes the direction of force. (f)<\/strong> An inclined plane always has the mechanical advantage more than 1. 2. Fill in the blanks<\/strong><\/p>\n (a)<\/strong> The useful work done by an actual machine is always less<\/strong> than the work done on the machine. 3. Match the following<\/strong><\/p>\n <\/p>\n Answer.<\/strong><\/p>\n 4. Select the correct alternatives<\/strong><\/p>\n (a)<\/strong> For an ideal machine, the efficiency is<\/p>\n (b)<\/strong> Mechanical advantage of a machine is defined as:<\/p>\n (c)<\/strong> The mechanical advantage of a lever is equal to:<\/p>\n (d)<\/strong> A pulley is used because it<\/p>\n (e)<\/strong> Wheel is used with axle because<\/p>\n B. Short\/Long Answer Questions<\/strong><\/span><\/p>\n Question 1.<\/strong><\/span> Question 2.<\/strong><\/span> Question 3.<\/strong><\/span> Question 4.<\/strong><\/span> Question 5.<\/strong><\/span> Question 6.<\/strong><\/span> Question 7.<\/strong><\/span> Question 8.<\/strong><\/span> Question 9.<\/strong><\/span> Question 10.<\/strong><\/span> Question 11.<\/strong><\/span> Question 12.<\/strong><\/span> Question 13.<\/strong><\/span> Question 14.<\/strong><\/span> Question 15.<\/strong><\/span> Question 16.<\/strong><\/span> Question 17.<\/strong><\/span> Question 18.<\/strong><\/span> Answer:<\/strong><\/span><\/p>\n Question 19.<\/strong><\/span> Question 20.<\/strong><\/span> Question 21.<\/strong><\/span> <\/p>\n <\/p>\n <\/p>\n Question 22.<\/strong><\/span> Question 23.<\/strong><\/span> Question 24.<\/strong><\/span> Question 25.<\/strong><\/span> Question 26.<\/strong><\/span> Question 27.<\/strong><\/span> Question 28.<\/strong><\/span> Question 29.<\/strong><\/span>\n
\nEfficiency = Work output \/ Work input<\/li>\n
\nThe levers are of three kinds :<\/strong>
\nClass I levers which have fulcrum in between the load and the effort.
\nClass II levers which have load in between fulcrum and the effort.
\nClass III levers which have effort in between the fulcrum and the load.<\/li>\n
\nAnswer.<\/strong> False<\/p>\n
\nAnswer.<\/strong> False<\/p>\n
\nAnswer.<\/strong> True<\/p>\n
\nAnswer.<\/strong> False<\/p>\n
\nAnswer.<\/strong> True<\/p>\n
\nAnswer.<\/strong> True<\/p>\n
\n(b)<\/strong> In class II levers, the load is in between fulcrum and effort.<\/strong>
\n(c)<\/strong> The mechanical advantage of class III<\/strong> lever is always less than 1.
\n(d)<\/strong> A pulley is used to change the direction of effort.<\/strong>
\n(e)<\/strong> Mechanical advantage of an inclined plane is always greater than 1.<\/strong><\/p>\n
\n<\/p>\n\n
\n
\n
\n
\n
\nWhen is work said to be done by a force ?
\nAnswer:<\/strong><\/span>
\nWork is said to be done when a force moves an obj ect through a distance in its own direction.<\/p>\n
\nWhat is energy ?
\nAnswer:<\/strong><\/span>
\nEnergy:<\/strong> The ability or capacity to do work is called energy.<\/p>\n
\nWhat do you understand by a machine ?
\nAnswer:<\/strong><\/span>
\nMachine:<\/strong> A machine is a device that allows us to do work with less effort. Machines make our work easier to do. Machines have made our li ves comfortable and faster.<\/p>\n
\nWhat is the principle on which a machine works ?
\nAnswer:<\/strong><\/span>
\nPrinciple of a Machine:<\/strong> The work output of a machine is equal to the work input.<\/p>\n
\nState two functions of a machine.
\nAnswer:<\/strong><\/span>
\nVarious functions that a machine can perform are:<\/p>\n\n
\nName six simple machines. Give an example of each machine.
\nAnswer:<\/strong><\/span>
\nThe Simple Machines and there examples are as follows:<\/p>\n\n
\nDefine the term \u2018work input\u2019 and \u2018work output\u2019 in relation to a machine.
\nAnswer:<\/strong><\/span>
\nWork input is work done on a machine equal to the effort force times the distance through which the force is applied.
\nWork output is work that is done by a machine equals resistance force times the distance through which the force applied.
\nFor an ideal machine, the work output is equal to the work input i. e. the efficiency.<\/p>\n
\nExplain the term mechanical advantage of a machine.
\nAnswer:<\/strong><\/span>
\nThe mechanical advantage of a machine is the ratio of the load to the effort. In other words
\n<\/p>\n
\nDefine the term efficiency of a machine.
\nAnswer:<\/strong><\/span>
\nThe ratio of the work done by the machine to the work done on the machine is called efficiency of a machine
\n
\n(Work done by a machine is called the output energy and the work done on a machine is called the input energy.)<\/p>\n
\nWhat is an ideal machine ?
\nAnswer:<\/strong><\/span>
\nA machine is which no part of the work done on the machine is wasted, is called an ideal or perfect machine. Thus, for an ideal machine, the work output is equal to the work input, i.e., the efficiency of an ideal machine is 1 (or 100 per cent).<\/p>\n
\nCan a machine have an efficiency of 100% ? Give a reason to support your answer.
\nAnswer:<\/strong><\/span>
\nEfficiency of a machine is always less than 100% as output energy is always less than the input energy, because some energy is lost to overcome friction.<\/p>\n
\nA machine is 75% efficient\u2019. What do you understand by this statement ?
\nAnswer:<\/strong><\/span>
\nIf a machine is 75% efficient, it means that 75% of the work input to the machine is obtained as the useful work output. The remaining 25% of the work input has been lost in overcoming the friction.<\/p>\n
\nWhat is a lever ?
\nAnswer:<\/strong><\/span>
\nLever:<\/strong> A lever is a simple rigid bar which is free to move around a point called fulcrum.<\/p>\n
\nDescribe three orders of levers giving an example of each. Draw neat diagrams showing the positions of fulcrum, load and effort in each kind of lever.
\nAnswer:<\/strong><\/span>
\nThe levers are of three kinds :<\/strong>
\nClass I levers which have fulcrum in between the load and the effort.
\n
\nClass II levers which have load in between the fulcrum and the effort.
\n
\nClass III levers which has effort in between the fulcrum and the Load
\n<\/p>\n
\nWhat do you mean by the mechanical advantage of a lever ?
\nAnswer:<\/strong><\/span>
\nThe mechanical advantage of a lever is equal to the ratio of the effort arm to the load arm. This is also called the principle of a lever.<\/p>\n
\nWhich class of lever has the mechanical advantage always more than 1 ? Give an example.
\nAnswer:<\/strong><\/span>
\nThe mechanical advantage of class II levers is always more- than 1.
\nExample – Nut cracker, wheel barrow, bottle opener etc.<\/p>\n
\nWhich class of lever has the mechanical advantage always less than 1 ? Give an example.
\nAnswer:<\/strong><\/span>
\nThe mechanical advantage of class III levers is always less than 1.
\nExample: a pair of tongs, sugar tongs, knife, forceps etc.<\/p>\n
\nGive one example of class I lever in each case where the mechanical advantage is<\/p>\n\n
\n
\nName the class to which the following levers belong:
\n
\nAnswer:<\/strong><\/span>
\n(a) A pair of scissors \u2014 Class I lever
\n(b) a lemon squeezer \u2014 Class II lever
\n(c) a nut cracker \u2014 Class II lever
\n(d) a pair of sugar tongs \u2014 Class III lever
\n(e) a beam balance \u2014 Class I lever
\n(f) an oar rowing a boat \u2014 Class I lever
\n(g) a wheel barrow \u2014 Class II lever
\n(h) a see saw \u2014 Class I lever
\n(i) a pair of pilers \u2014 Class I lever
\n(j) a crow bar \u2014 Class I lever<\/p>\n
\nThe diagram given below shows the three kinds of levers. Name the class of each lever and give one example of each class.
\n
\nAnswer:
\n<\/strong><\/span>
\nExamples : The examples of class I levers are : a see saw, a pair of scissors, a pair of pilers, crow bar, common balance, spoon opening the lid of a tin can, handle of a hand pump.
\n
\nExamples : The examples of lever of class II are : nut cracker, wheel barrow, paper cutter, mango, lemon squeezer, bottle opener.
\n
\nExamples: The examples of levers of class III are : a pair of tongs, sugar tongs, knife, forceps,-forearm of a person holding a load, spade for lifting soil or coal.<\/p>\n
\nDraw diagrams to illustrate the positions of fulcrum, load and effort, in each of the following:
\n(a) a see saw
\n(b) a beam balance
\n(c) a nut cracker
\n(d) a pair of forceps
\nAnswer:
\n
\n<\/strong><\/span><\/p>\n
\nHow can you increase the mechanical advantage of a lever ?
\nAnswer:<\/strong><\/span>
\nThe mechanical advantage of a lever can be increased by increasing the effort arm or reducing the load arm.<\/p>\n
\nHow does the friction at the fulcrum affect the mechanical advantage of the lever ?
\nAnswer:<\/strong><\/span>
\nFriction at the fulcrum reduces the mechanical advantage.<\/p>\n
\nState three differences between the three classes of levers.
\nAnswer:
\n
\n<\/strong><\/span><\/p>\n
\nWhat is a pulley ?
\nAnswer:<\/strong><\/span>
\nPulley: It is a flat circular disc with a groove in its edge and a rope passing through the groove. It is capable of rotating around a fixed point passing through its central axis called axle.<\/p>\n
\nWhat is the mechanical advantage of an ideal pulley ?
\nAnswer:<\/strong><\/span>
\nIn an ideal pulley, the effort applied is equal to the load to be lifted.
\ni.e. Effort = Load
\nMechanical advantage = Load \/ Effort = 1<\/p>\n
\nThe mechanical advantage of an actual pulley is less than 1. Give a reason. What is the justification for using the pulley then ?
\nAnswer:<\/strong><\/span>
\nIn an actual pulley due to friction, the mechanical advantage is less than 1 (i.e. the effort is more than the load).
\nThe reason for using the pulley when its mechanical advantage is equal to 1 or less than 1 is that the pulley allows us to apply the effort downwards i.e. in a convenient direction. To raise a load directly upwards is difficult. But with the help of a pulley, the effort can be applied in the downward direction to move the load upwards. One can hang on it to make use of his own weight also in order to apply the effort.<\/p>\n
\nDraw a neat labelled diagram showing a pulley being used to lift a load. How are load and effort related in an ideal situation?
\nAnswer:<\/strong><\/span>
\nTo raise a load, the load is attached to one end of the string and the effort is applied at the other end by pulling it is downward direction . as shown in fig.
\n<\/p>\n
\nWhat is an inclined plane? What is its use ? Give two examples where \u00a1t is used.
\nAnswer:<\/strong><\/span>
\nAn inclined plane is a rigid sloping surface over which heavy loads can be raised or lowered to a certain height or depth.
\nThe mechanical advantage of an inclined plane is the ratio of the length of the plank to the vertical height of the load raised. Its value is greater than one. Therefore, an inclined plane acts as a force multiplier. Thus, it can be used to lift heavy loads.
\nExample : If a heavy box needs to be loaded on a lorry, it is far easier to push it over an inclined plane than to lift it up. Steeper the inclined plane, greater will be the effort required to push up the load.
\nSloping ramps, flyovers, roads on hills and staircases are all examples of inclined planes.<\/p>\n