An object with a known mass, say one kilogram, is moving in a direct line (say from West to East) from point 1 to point 2 with a known speed, say one meter per second. At 2 a force acts on the object. The force does not change the object's speed, but does change its direction of motion by 45 degrees (to the South East). Is it theoretically possible to calculate how strong the force was?
a) Yes, the strength of the force can be calculated (though I might not know how to do the calculation).
b) No, the force cannot be calculated by anyone.
2007-09-16 16:07:58 · 3 answers · asked by ? 6 in Science & Mathematics ➔ Physics
The answer is b. You can't tell. The story here is very much like the story in my question titled Rocket Sled. The turn could be made by a small force acting acting over a long time or a large force acting for a short time. If the force is small and the time long, the turn will be gradual. But if the force is strong and the time is short the turn will be abrupt. If the turn is instantaneous, the force would have to be infinitely large. So, perfectly sharp turns do not exist in nature.
If an object goes around a bent path, the force is on some of the time and off at other times. The force is on in the curves, and off in the straight parts. Often it is convenient to talk about the average force. If the object goes around a smooth circular path, however, then the force is exactly equal to the average force.
2007-09-19 15:20:00 · update #1
a) Yes the strength of the force can be calculated.
I think so because, I have a very practical and common example of this. A body moving in circular motion. It is not necessary for the speed to change. One can go about in a circle with a constant speed. Also the force on the body can also be calculated.
Apart from this example even if one thinks logically, the situation is neither very special nor does it violate any laws of physics (to my knowledge) so why should it remain unknown or unpredictable. It can definitely be calculated.
2007-09-17 20:29:28 · answer #1 · answered by D 2 · 0⤊ 0⤋
a, assuming known or absent friction and knowledge of the duration of the force. The lateral velocity change is 1 m/s, and from Newton, f = ma = mΔv/Δt.
EDIT: However, as lin noted, since the question didn't provide Δt there is no solution.
2007-09-16 16:39:08 · answer #2 · answered by kirchwey 7 · 0⤊ 0⤋
a
2007-09-16 16:18:41 · answer #3 · answered by Joe S 1 · 0⤊ 0⤋