unit 4 Flashcards
a system
-an object or a collection of objects
-treated as having no internal structure
-interactions can occur between the objects within a system or between objects of different systems)
2 ways interactions can occur:
-a force is exerted by objects outside the system or between objects with the system
-a transfer/ exchange of some quantity with objects outside the system or between objects within the system
work is done if…
a force is applied over a specified displacement
work
the transfer of energy to or from a system
for work: if the angle is 90 then the work is ____
0
work: if the angle is less than 90 then the work is ___
positive
work: if the angle is greater than 90 then the work is ___
negative
if + work then…
total mechanical energy increases
if negative (-) work then…
total mechanical energy decreases
if no external force acts on a system then…
the ME will not change
if all forces are internal then
-no work is done ON the system
-but work can be done WITHIN the system
work energy theorem
work done on an object is equal to the change in KE of the object
