Question

Advantage of simple machine

Answer 1

ADVANTAGE OF SIMPLE MACHINE
1)For an ideal machine, the input work and output work are always same.
2) The six common machines are: the lever,wheel and axle,pulley,inclined plane,wedge and screw.
3) For all simple machine, the ideal mechanical advantage is.

Answer 2

A machine is an object or mechanical device that receives an input amount of work and transfers the energy to an output amount of work. For an ideal machine, the input work and output work are always the same. Remember that work is force times distance; even though the work input and output are equal, the input force does not necessarily equal the output force, nor does the input distance necessarily equal the output distance.

Machines can be incredibly complex (think of robots or automobiles), or very simple, such as a can opener. A simple machine is a mechanical device that changes the magnitude or direction of the force. There are six simple machines that were first identified by Renaissance scientists: lever, pulley, inclined plane, screw, wedge, and wheel and axle. These six simple machines can be combined together to form compound machines.

We use simple machines because they give us a mechanical advantage. Mechanical advantage is a measurement of the force amplification of a machine. In ideal machines, where there is no friction and the input work and output work are the same,

(Effort Force)(Effort Distance)=(Resistance Force)(Resistance Distance)

The effort is the work that you do. It is the amount of force you use times the distance over which you use it. The resistance is the work done on the object you are trying to move. Often, the resistance force is the force of gravity, and the resistance distance is how far you move the object.

The ideal mechanical advantage of a simple machine is the ratio between the distances:

IMA=effort distanceresistance distance

Again, the IMA assumes that there is no friction. In reality, the mechanical advantage is limited by friction; you must overcome the frictional forces in addition to the resistance force. Therefore, the actual mechanical advantage is the ratio of the forces:

AMA=resistance forceeffort force

When simple machines are combined to form compound machines, the product of each simple machine's IMA gives the compound machine's IMA.

Simple Machines
Lever

A lever consists of an inflexible length of material placed over a pivot point called a fulcrum. The resistance is the object to be moved (shown here in red), and is placed to one side of the fulcrum. The resistance distance in a lever is called the resistance arm. The effort is exerted elsewhere on the lever, and the effort distance is called the effort arm or effort lever arm. The lever shown here is the most common type of lever, a Class One Lever, but there are two other types of levers.

Diagram of a class one lever

[Figure2]
The effort work is the effort force times the effort lever arm. Similarly, the resistance work is the resistance force times the resistance lever arm. If we ignore any friction that occurs where the lever pivots over the fulcrum, this is an ideal machine. Suppose the resistance force is 500. N, the resistance arm is 0.400 m, and the effort arm is 0.800m. We can calculate exactly how much effort force is required to lift the resistance in this system:

Output Work=Input Work

(Resistance Force)(Resistance Arm)=(Effort Force)(Effort Arm)

(500. N)(0.400 m)=(x)(0.800 m)

x=250. N

In this case, since the effort arm is twice as long as the resistance arm, the effort force required is only half the resistance force. This machine allows us to lift objects using only half the force required to lift the object directly against the pull of gravity. The distance the effort force is moved is twice as far as the resistance will move. Thus, the input work and the output work are equal.


Example 1

(a) How much force is required to lift a 500. kg stone using an ideal lever whose resistance arm is 10.0 cm and whose effort arm is 2.00 m?

(b) What is the IMA?

(c) If the actual effort force required to lift the stone was 305 N, what was the AMA?

(a) (resistance force)(resistance arm)=(effort force)(effort arm)

effort force=(resistance force)(resistance arm)(effort arm)=(4900 N)(0.100 m)(2.00 m)=245 N

(b) IMA=effort armresistance arm=2.00 m0.100 m=20

(c) AMA=resistance forceeffort force=4900 N305 N=16
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