Physics, 02.10.2020 23:01, babydoll022299

What is impossible for a machine to do? A. do a greater amount of work than the amount of work done on the machine
B. apply a force in a direction that is different than the direction of the force applied to the machine
C. move an object a greater distance than the distance that part of the machine was moved
D. apply a force that is less than the force that is applied to the machine

Answers: 3

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answered: binava

Choice A. Without energy storage, the total work output of a machine will not exceed the total work input.

Explanation:

Choice A

Work is the product of force and the distance travelled in the direction of that force.

Indeed, simple machines can alter the size or direction of a force. However, their work output can't exceed the work input to that machine (unless the machine stores some energy- by bending, for example.) Because of frictions and other forms of energy loss, the useful work output of a real machine can even be smaller than the work input to that machine.

The force output of some machines can certainly exceed their force input. However, at the same time, the input part of those machine needs to move a distance that is (more than) proportionally longer compared to the output part of the machine. As a result, the useful work output would be equal to or even smaller than the total work input.

Choice B

A fixed pulley is an example of a machine that applies a force in a direction different from the direction of the force applied to the machine. Pulling the string down will lift up the weight on the other side. A seesaw (a first-class lever) is another real-world example of this kind of machines.

Choice C and D

Tongs are examples of machines where: the distance traveled by the output exceeds that of the input. However, that comes at a price: delivering the same amount of force with a pair of tongs requires more force than without a pair of tongs. That corresponds to choice D: the work output of some machines can be less than the force input to these machines.

At the same time, some extra force input might be required to overcome the friction between parts of the machine. That's another reason why the machine applies less force than the input even if it was designed to apply the same amount of force.

answered: Guest

Fitness is the ability to perform only very light levels of physical activity.

answered: Guest

technology is the application of the knowledge gained by science.

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What is impossible for a machine to do? A. do a greater amount of work than the amount of work done...