Differences between revisions 8 and 13 (spanning 5 versions) Back to page
Revision 8 as of 5:03PM, Sep 29, 2011
Size: 870
Editor: Sam
Comment:
Revision 13 as of 10:14PM, Oct 03, 2011
Size: 735
Editor: Sam
Comment:
Deletions are marked like this. Additions are marked like this.
Line 5: Line 5:
  A. Gravitational force
  A. Electromagnetic force
  A. Strong force
  A. Weak force
  A. Gravitational interaction
  A. Electromagnetic interaction
  A. Strong interaction
  A. Weak interaction
Line 10: Line 10:
Ans. A Ans. A. An electromagentic interaction refers to the interaction of two electrically charged objects by exchanging photons.
Line 19: Line 19:
Ans. What do you mean by contact? Does exchanging photons/gravitons count as contact? On a more practical level, it is helpful to remember, "no contact, no force except gravity, in ''most'' problems of classical mechanics".

= The work energy "theorem" =

The work energy theorem, $\Delta T = W$ where $T$ is the kinetic energy (and $\Delta T = T_2 - T_1$ is its change) and $W$ is the net work done on the particle, is

  A. always valid (in classical mechanics).
  A. valid only for conservative forces.
Ans. What do you mean by contact? Does exchanging photons or gravitons count as contact? On a more practical level, it is ''very'' helpful to remember, "no contact, no force except gravity," in ''most'' problems of classical mechanics.

Which force?

Friction, air resistance, tension, spring force, normal force, etc. are all due to

  1. Gravitational interaction
  2. Electromagnetic interaction
  3. Strong interaction
  4. Weak interaction

Ans. A. An electromagentic interaction refers to the interaction of two electrically charged objects by exchanging photons.

The force is everywhere

When two objects exchange forces, they can do so without having to contact each other.

  1. Yes
  2. No

Ans. What do you mean by contact? Does exchanging photons or gravitons count as contact? On a more practical level, it is very helpful to remember, "no contact, no force except gravity," in most problems of classical mechanics.