Study Guide for Simple Machines

 

Questions:

 

1.       What are the three types of advantage of simple machines? In order to make these gains what do we give up?

2.     What are the two equations for the efficiency of a machine?

3.     What simple machine in the real world is based on a class 1 lever?

4.     What simple machine in the real world is based on a class 2 lever?

5.     What simple machine in the real world is based on a class 3 lever?

6.     If the IMA of a lever is 2, could the lever be a class 3 lever?

7.     If the IMA of a lever is 2, could the lever be a class 2 lever?

8.     If the IMA of a lever is 1, what type of lever will it be?

9.     If the IMA of a class 1 lever is 4 and you lift the resistance 1 meter, how far down will you have to push the opposite end of the lever?

10.  How does the force of friction affect IMA of an inclined plane?

11.   How does the force of friction affect the AMA of an inclined plane?

12.  How could you increase the IMA of a staircase in order to allow a handicapped person negotiate it better?

13.  If the IMA of a ramp is 10 and the height of the ramp is 14 feet, how long is the ramp?

14.  What is the IMA of the pulley system shown?

15.  How could you increase the IMA?

16.  How far would you have to pull the effort in order to lift the resistance 1.5-m?

17.  In real life, how can a pulley system or block and tackle be used for speed advantage?

18.  Think of a simple machine that utilizes a wheel and axle.  Could the device still be used if the wheel were removed?

19.  What problems would exist if we try to increase the IMA of a wheel and axle by significantly changing the size of the axle?

20.Both mountain bikes and road bicycles utilize wheel and axles in their gearing systems.  How might a mountain bikes gearing system differ from a road bike?

21.  Bicyclists often use the term “gear-ratio”.  What term in physical science do you think is similar?

22.How would you increase the IMA of a wedge?

23.How would you increase the IMA of a screw?

24.Can you think of a tool that utilizes a wedge other than a wedge used to split wood?

25.How could you determine the length of a thread on a screw given only the number of threads and the diameter of a screw?

26.Can you think of machines that utilize screws?

27.List and describe the three types of advantage utilized by simple machines.

28.Is it possible for a machine to have an efficiency over 100%? Explain your answer.

29.What is the Ideal Mechanical Advantage of a lever? Actual Mechanical Advantage?

30.How could you determine the IMA of a block and tackle pulley system?

31.  What type of simple machines are the following: Please briefly explain your answer. 
Wood Splitting Mall ______________. 
Screw Driver  ________________.  
Canoe Paddle ________________.  
Door Knob _________________.  
Bicycle Gears _______________.

32.How is a wheel and axle like a lever?

33.How could you increase the mechanical advantage of the following machines?                   a.) 1st class lever                  b.) 2nd class lever             c.) pulley system

 


 

Problems:  Please answer the following problems.  Show your work and formulas to receive full credit. (Hint:  Draw the machine.)

 

1.       A first class lever is used to pry open a manhole cover that weighs 980-N.  The total length of the bar is 1.5-m and the fulcrum is placed 0.1-m from the manhole cover.  A sewer worker needs to apply a force of 71-N to lift the cover.             
a.) What is the IMA of the lever?                               
b.) What is the AMA of the lever?                              
c.) What is the efficiency of the lever?

2.     A lever is used to lift a weight of 30-N.  The AMA of the lever is 0.4.
a.) What will be the effort force needed to lift the weight.
b.) What type of advantage may be gained by this lever?

3.     A 200-N cart is rolled up a 1.5-m ramp to a height of 0.5-m.  The force needed to push the cart is 68-N parallel to the ramp.   
a.) What is the AMA?
b.) What is the IMA?
c.) What is the "input work" ?                                              
d.) What is the "output work"?                                   
e.) What is the efficiency?

4.     A pulley system is used to lift an engine out of a truck.  The system has an ideal mechanical advantage of 8.  The engine weighs 579 lbs.        
a.) What is the minimum force needed to pull the haul rope?
b.) How far will you have to pull the haul rope?     

Answers