1. The Apple, Hand and the Earth
Created for BW Physics By
Dick Heckathorn
5 March 2K + 8

2. 2.

3. w is exerted by earth on apple.
Fe on apple

4. n is exerted by hand on apple.
Fhand on apple n

5. How is Fh on a related to Fe on a?
Fhand on apple
(equal)
(same magnitude) ?
Are not equal as they are in opposite directions.
Fe on apple
3b.

6. What is the net force on the apple?
Fhand on apple
(zero)
(nonzero) ?
Why?
The apple is not moving.
Fe on apple
3d.

7. Note that both forces are acting on the same object.
are they an action-reaction pair?
Since Fh on a and Fe on a are equal & opposite,
(they are)
Fhand on apple
(they are not) ?
Note that both forces are acting on the same object.
Fe on apple
3d.

8. The reason is…they act on:
Fhand on apple
the same object
different objects ?
Thus we can say…
Fe on apple
3d.

9. If the action force is the earth pulling on the apple then
the reaction force is the
apple pulling on the earth.
Fa on earth
Fearth on a
3d.

10. Thus we can see that Fh on a and Fe on a are
Fhand on a
equal and opposite and… do
do not
comprise an action-reaction pair.
Fearth on a
3f.

11. Another pair of forces are… comprise and action-reaction pair.
Fhand on apple
This force pair
does
does not
comprise and action-reaction pair.
Fapple on hand
3g.

12. There is a net force up on the apple of 2-N
Nellie now pushes upward with her hand on the apple with 2-N of additional force.
What does the apple do?
still at rest
accelerates up
New
Fhand on a
Why?
There is a net force up on the apple of 2-N
Fa on hand
3h.

13. The force of the hand on the apple is: the net force on the apple is:
Once the apple leaves the hand…
The force of the hand on the apple is:
Fh on a
the net force on the apple is:
Thus the apple
begins to slows down.
Fe on apple
3d.

14. That’s all folks!