mechanical advantage

mechanical advantage of different types of machines

Many machinesincluding inclined planes such as rampsincrease the strength of the force put into the machine but decrease the distance over which the force is applied. Other machines increase the distance over which the force is applied but decrease the strength of the force. Still other machines change the direction of the force, with or without also increasing its strength or distance. Which way a machine works determines its mechanical advantage, as shown in the Table 1.1. Strength of Force increases decreases stays the same (changes direction only) Distance Over Force is Applied decreases increases stays the same which Mechanical Advantage Example >1 <1 =1 ramp hammer flagpole pulley

a simple example

Look at the ramp in the Figure 1.1. A ramp is a type of simple machine called an inclined plane. It can be used to raise an object off the ground. The input distance is the length of the sloped surface of the ramp. This is the distance over which the input force is applied. The output distance is the height of the ramp, or the vertical distance the object is raised. For this ramp, the input distance is 6 m and the output distance is 2 meters. Therefore, the ideal mechanical advantage of this ramp is: Input distance Ideal Mechanical Advantage = Output distance = 62 m m =3 An ideal mechanical advantage of 3 means that the ramp ideally (in the absence of friction) multiplies the input force by a factor of 3. The trade-off is that the input force must be applied over a greater distance than the object is lifted. Q: Assume that another ramp has a sloping surface of 8 m and a vertical height of 4 m. What is the ideal mechanical advantage of this ramp? A: The ramp has an ideal mechanical advantage of: Ideal Mechanical Advantage = 84 m m =2

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ideal mechanical advantage

It can be difficult to measure the input and output forces needed to calculate the actual mechanical advantage of a machine. Generally, an unknown amount of the input force is used to overcome friction. Its usually easier to measure the input and output distances than the input and output forces. The distance measurements can then be used to calculate the ideal mechanical advantage. The ideal mechanical advantage represents the change in input force that would be achieved by the machine if there were no friction to overcome. The ideal mechanical advantage is always greater than the actual mechanical advantage because all machines have to overcome friction. Ideal mechanical advantage can be calculated with the equation: Ideal Mechanical Advantage = Input Distance Output Distance

what is mechanical advantage

How much a machine changes the input force is its mechanical advantage. Mechanical advantage is the ratio of the output force to the input force, so it can be represented by the equation: Actual Mechanical Advantage = Output force Input force Note that this equation represents the actual mechanical advantage of a machine. The actual mechanical advantage takes into account the amount of the input force that is used to overcome friction. The equation yields the factor by which the machine changes the input force when the machine is actually used in the real world.

instructional diagrams

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questions

ways that machines may make work easier include changing the

a) amount of force applied.

b) distance over which force is applied.

c) direction in which force is applied.

-->  d) any of the above

the equation for calculating actual mechanical advantage is

a) actual mechanical advantage = input force/output force.

b) actual mechanical advantage = input distance/output distance.

-->  c) actual mechanical advantage = output force/input force.

d) actual mechanical advantage = output distance/input distance.

the equation for calculating ideal mechanical advantage is

a) ideal mechanical advantage = input force/output force.

-->  b) ideal mechanical advantage = input distance/output distance.

c) ideal mechanical advantage = output force/input force.

d) ideal mechanical advantage = output distance/input distance.

the mechanical advantage of a machine may be less than, equal to, or greater than 1.

-->  a. true

b. false

diagram questions

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