Integrated Physics and Chemistry TEKS Correlations
(4) Science concepts. The student knows concepts of force and motion evident in
everyday life. The student is expected to:
(D)investigate and demonstrate mechanical advantage and efficiency of various machines such as levers, motors, wheels and axles, pulleys, and ramps.
84.
For a simple machine to reduce the amount of force needed to do work, which of the following must
increase?
A.
B.
C.
D.
85.
Lubricants like motor oil and grease help increase a car’s efficiency by 
A.
B.
C.
D.
86.
The mass of the object that needs to be moved
The distance the effort force moves
The friction between the parts of the simple machine
The number of parts in the simple machine
reducing the amount of tire surface in contact with the ground
increasing the energy content of the fuel
reducing the friction between the moving parts
increasing the amount of force the wheels apply
If a machine is 46% efficient and can provide 85 joules of work output, approximately how much work
must be put into the machine?
A.
B.
C.
D.
39 joules
54 joules
130 joules
180 joules
These items (84-86) illustrate the many ways that efficiency of simple machines can be
approached. The last item is simple calculation, whereas the first two items are more
conceptual. Students may find the first two items much harder than the last. They can easily
plug numbers into formulas, but rarely investigate machines to see that forces and distances
change when applied to different machines or that there are things that can be done to a
machine to make it more efficient.
Charles A. Dana Center
Science TEKS Toolkit
www.sciencetekstoolkit.org