Machine – Science
Machine • The device or instruments, which make our work easier, faster and convenient are called simple machines. Lever, Wheel & axel, Pulley, Inclined plane, Screw and Wedge are simple machines. • Mechanical Advantage: The ratio between load raised and effort applied in a simple machine is called mechanical advantage. It has no unit as it is a simple ratio of two forces. It is affected by friction. M.A.= Load(L) Effort(E)
Machine Velocity ratio: The ratio between distance travelled by the effort and the distance travelled by the load is called velocity ratio. It has no unit because it is a simple ratio of two distances. It is not affected by friction. V.R = E.D/L.D Efficiency: The percentage ratio output work to the input work is called efficiency. • Efficiency = work done by the machine/work done on the machine In another way, it can be defined as the ratio of output work to the input work. It is expressed in terms of percentage.