SCIENCE STD. V (2015) More About Force Energy and Simple Machines Name Roll No. Date Std. V Q1.What is Force? Force is a push or a pull that makes the things move. Q2.What effect does Force has on our day to day life? Force changes the direction of a moving object, Changes the shape of an object, Makes an object move and Stops a moving object. Q3.What are the main types of force? Explain each by giving examples for each type. Main types of forces used in our day today life are Magnetic Force, Gravitational Force, Frictional Force and Electrostatic Force. Magnetic Force: When a magnetic dart is thrown on a metallic board it exerts a force and sticks to it. This type of f orce is called a Magnetic Force. 1
Gravitational Force: An object always fall towards the ground and never moves up in the sky because of the Earths gravity. The force exerted by it is called Gravitational force. Frictional Force: Whenever two objects rub against each other,there is a force that prevents them to glide smoothly. This force is called Frictional Force. Electrostatic Force: When the electricty is produced in an object it exerts a force it is called Electrostatic Force. 2
4. What is the use of Friction? Friction helps us in the following manner: It helps us to write on paper with a pencil or pen It helps us to drive the car or bicycle on the road without slipping. It helps us to walk safely and without slipping and falling. Rubbing hands together produces heat due to friction. Q5.What difficulties can Friction create for us? Friction can cause difficulty in sliding a heavy body across the floor. It can wear out the moving parts of any objects. Q6. What is Energy? Energy is the ability of a body to do work. Q7. State some different kinds of energies and their uses. Type of Energy Uses E.g. Light Energy Helps us to see things around Sun, bulb Heat Energy Makes us feel the heat. Burning of wood,coal and candle Sound Energy Makes us hear the sound. Musical instruments, fire crackers and human sounds. Electrical Energy Helps us to run appliances. Computers, fans,light bulbs,washing machines etc. Q1. What are Machines? MACHINES Machines are things which make work easier for us. Q2.What are Simple Machines and Complex Machines? Simple Machines have very few parts like spoon, tweezer,tong etc. and Complex Machines are made up from two or more Simple Machines such as washing machines cranes etc. 3
Q3.How many types of Simple Machines are there? There are five types of Simple Machines. Lever, Pulley, Inclined plane, Screw and Wheel and Axle. Q4.What is a lever? A lever is a rigid rod fixed at a point called the fulcrum. Q5 How many parts does a lever have? Name them and define them. A Lever has three parts Fulcrum, Effort and Load.Fulcrum: It is a fixed point about which the rod moves. Effort:It is the part where force is applied Load: It is the part on which the work has to be done. Q6 How many kinds of levers are there? Explain their kind. Give examples of the same. Levers are of three kinds. First Class Lever, L F E Second Class Lever F L E Third Class Lever F E L First Class Lever: IN this the Fulcrum is in the centre and load and effort are at the two ends. Eg. Beam balance, Sea saw,and scissors. 4
Second Class Lever: In this lever load lies between the fulcrum and Effort. Eg. Nut cracker, lemon squeezer, Wheel Barrow. Third Class Lever: In this lever Effort is in between the Fulcrum and Load. Eg. Tweezers, tongs and fishing rod. Q7. Describe a Pulley. State its working. A pulley is a wheel with a groove and a rope or a chain to move around it. If we pull the load up, we work against the Gravity and it requires more effort than when we release the load downwards. A pulley is also used to lift the heavy engines and fit them into vehicles. Flags are also hoisted on a flag post. 5
Q8.What is an inclined plane? What are the uses of having an Inclined plane? How is it possible to climb a road on a hilly region? An inclined plane is a gentle slope. It helps to move a heavy load with lesser effort. Uses: It is used in a hospital like a ramp to push the wheel chairs and stretchers. Roads in a hilly region are also like an inclined plane with a gentle slope. It makes it easier to make the vehicles to move up. Q9..Explain how a screw is a simple machine? Screw is a simple machine because it is like an inclined plane A screw has grooves cut into it. The head of a screw also has a groove. A screwdriver is fixed into this groove and rotated, Due to the spiral grooves the screw moves in the wood easily. It also holds the wood firmly. Q10. Whats a Wheel and Axle.? A wheel and axle has a large wheel connected to a small rod The two are fixed so that they move together. When the axle is turned the wheel also moves. *************** 6