Why is It So Easy to Overcome Resistance Force in a Screw

On this page:

• Create a table with a sample of each simple machine, characteristics, and formulas for mechanical advantage.
• Insert photographs and Inventor pictures of your Compound Machine.  Describe the process you followed to create your machine and its mechanical advantage.
  
• Answer the Essential Questions for 1.1
• Attach Activities 1.1.1 - 1.1.6.

1.1.1 Simle Machine Test

In lesson 1.1.1 we tested the IMA, AMA, and efficiency of all the simple machines (lever, inclined plane, screw, wheel and axle, and pulley)

The following are calculations of the simple machines that I observed

1st Class Lever

 AMA=10/9

 2nd Class Lever

IEF= 107.5

3rd Class Lever

IMA=.54

1. Is it possible for a first or second class lever to have a mechanical advantage less than one, or for a third class lever to have a mechanical advantage greater than one? Justify your answer.

2. No, a second class lever always has a mechanical advantage over 1.

3. No, a third class lever always has a mechanical advantage less than 1.

 1. When you were solving for mechanical advantage, what units did the final answer require? Explain why.

The final answer required grams and centimeters. The actual mechanical advantage required grams to measure the force. The ideal mechanical advantage required centimeters to measure the distance for the distance effort and distance resistance.

1.  For the same resistance, is the effort force larger when the effort is applied to the wheel or when it is applied to the axle?  Explain why.

2. The axle, because it has less distance effort, but consequently it requires more force resistance.

1. List and describe two examples of a wheel and axle.

2. Doorknob

3. Steering wheel

4. If you know the dimensions of a wheel and axle system used for an automobile, how can you determine the distance covered for each axle revolution? Explain any additional information and necessary formulas.

5. By using the dimension for the circumference (2 * pi * r), you can calculate the distance covered  for the axle revolutions.

6. Why is the steering wheel on a school bus so large?

7. Because it takes less effort force to move it, but consequently it also takes a larger to distance to turn the wheel.

1.1.2 VEX1. The fixed pulley contained two strands. Explain the role of each strand.

2. One of the strands was used to pull to apply the effort force. The other was used to attach the effort resistance to.

3.  The movable pulley contained two strands. Explain the role of each strand.

4. One of the strands was used to act as a steady base so that the pulley didn't move. The other strand was used to hook onto the moveable part of the pulley and  have the effort force applied to it.

5. In the block and tackle system, explain how mechanical advantage relates to the number of strands.

6. The ideal mechanical advantage is decided by the number of strands in the pulley.

7. In a block and tackle system with a mechanical advantage of 3, the effort is measured at 15 lbf. The resistance, when balanced, is measured at 42 lbf. What factors might account for the loss in energy?

8. The block and tackle system could be affected by friction of the rope on the pulley and the pulley on the axle. It could also be affected by sound.

1. List and describe two examples of an inclined plane.

2. Ramps

3. Escalators

1. Why do you think overcoming a resistance force using a screw is so easy?

Because of the lack of friction caused by the screw. Also, the effort force needed to move objects is less than other simple machines.

2.  The screw is a combination of two simple machines. Identify and defend what two simple machines you believe are combined to create a screw.

3. An inclined plane and a wheel and axle are used. The threads go along the inner edges of the implementing screw which is like an inclined plane. The screw is like a wheel and axle because the head of the screw is like the axle and the thread part is the wheel.

1.1.3 PoE

In this assignment we calculated the gear ratios of different gears based off of the information that was given to use. In the case below, we were given the number of teeth on the gears and had to find the gear ratio of all the gears based off that.

1.1.4 Pulley Drive Sprockets

In this activity we were given a picture of a gear system and had to figure out if they were going clockwise or counterclockwise. With this information we were given the diameter and from that we had to find out the gear ratio of all the gears in the system. Below is a table of the calculations that I did based off the information that I was given in the picture of the gear system. The first gear had a diameter of 6 in, the B gear had a diameter of 3 in, the C gear had a diameter of 10 in, and the D gear had a diameter of 8 in.

1.1.5 Gears Pulley Drives Sprockets Practice Problems

In this activity we were given differnt information about the gears and/or pulleys such as the diameter and speed that it was moving in this case, and with this information we had to find information about other geras or pulleys in the system that we didn't have for.

1.1.6 Compound Machine Design VEX

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Source: https://sites.google.com/site/20122013poeaustins/home/academics/finearts

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