Q1 define the term efficiency of a machine
Q2 what is an ideal machine
Q3 Can a machine have an efficiency of a 100% ?give a reason to support your answer
Q4 'a machine is 75% efficient' what do you understand by this?
Q5 what is a lever?
Q6 describe three orders of levers giving an example of each
Answers
1.Mechanical efficiency is a dimensionless number that measures the effectiveness of a machine in transforming the power input to the device to power output. A machine is a mechanical linkage in which force is applied at one point, and the force does work moving a load at another point.
2 The term ideal machine refers to a hypothetical mechanical system in which energy and power are not lost or dissipated through friction, deformation, wear, or other inefficiencies.
3 Machine Efficiency
The output work is always less than the input work because some of the input work is used to overcome friction. Therefore, efficiency is always less than 100 percent. The closer to 100 percent a machine's efficiency is, the better it is at reducing friction.
4.If 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.
5.A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is divided into three types. Also a leverage is a mechanical advantage gained in a mechanical system. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage of the lever. As such, the lever is a mechanical advantage device, trading off force against movement.
6.The levers are of three kinds:
Class I levers are which have fulcrum in between the load and the effort.
Eg. See-Saw
Class II levers which have load in between the fulcrum and the effort
Eg. - Nut- Cracker
Class III levers which has effort in between the fulcrum and the Load
Eg. Forceps.