Simple Machine-Law of Machine ► EN NO GUIDED BY EN NO PROF. V.R.SHARMA GEC PALANPUR APPLIED MECHANICS DEPARTMENT
Machines ► A device that makes work easier. ► A machine can change the size, the direction, or the distance over which a force acts.
What is Machine ? A simple machine has few or no moving parts. Simple machines make work easier
Simple Machine ► Simple machine is a device in which effort is applied at one place and work is done at some other place. ► Simple machine are run manually, not by electric power. ► e.g. -pulley -Wheel and axel -Wheel and axel -simple screw jack, etc. -simple screw jack, etc.
Simple Machine ► Simple Machines can be put together in different ways to make complex machinery
Law of machine For a particular machine, if we record various values of effort required to lift the corresponding load, we shall get a straight Mathematically, P=mW + C Where, P=effort applied Where, P=effort applied W=load lifted W=load lifted m=constant (coefficient of friction) m=constant (coefficient of friction) C=constant (machine of friction) C=constant (machine of friction)
Pulleys ► Pulley are wheels and axles with a groove around the outside ► A pulley needs a rope, chain or belt around the groove to make it do work
Simple Pulley
Diagrams of Pulleys Fixed pulley: A fixed pulley changes the direction of a force; however, it does not create a mechanical advantage. Movable Pulley: The mechanical advantage of a moveable pulley is equal to the number of ropes that support the moveable pulley.
Simple Wheel and Axle wheel axle ► The axle is stuck rigidly to a large wheel. Fan blades are attached to the wheel. When the axel turns, the fan blades spin.
Different Wheel and Axle and Their velocity ratio Different Wheel and Axle and Their velocity ratio ► Velocity ratio (VR) = distance moved by effort _________________________________________________________________________ distance moved by load
Screw The mechanical advantage of an screw can be calculated by dividing the circumference by the pitch of the screw. Pitch equals 1/ number of turns per inch. A screw is an inclined plane wrapped around a shaft or cylinder. The inclined plane allows the screw to move itself when rotated.
Screws ► Screw: an inclined plane wrapped around a cylinder threads Which screw would be easier to put into a piece of wood? -A screw with the threads very close together or a screw with the threads somewhat far apart -The screw with threads CLOSE together! -Though it would take you less turns for the screw with fewer threads, it would require you to exert a greater force
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