You pull a tablecloth so fast from under a table that the silverware above it does not move very much.
How does the physics of that work?
How does the physics of that work?
v--> c, so the items on top just stay there
Sorry was just trolling on that one a bit. v->c (speed of light), leaves everything behind.
i don't know why the stuff stays there. But it does move a little.
Or maybe it overcomes the static friction so much that it becomes sliding friction? And a combination of change in momentum?
delta p = 0, the cloth m << than silverware m, so when you pull the cloth at high v the silverware don't move so much?
The force acting on the dishes is friction from the table cloth. It's fairly limited - it depends on the cloth, speed that you're pulling and mass of dishes. If that force is F, the total impulse transferred to the dishes is F.t where t is the time that it takes to pull the table cloth away. If t is small enough, the impulse is small enough too and the dishes are not disturbed.
for such instances, momentum is usually constant, yes? so changing t will change f, not momentum. therefore, p=Ft, a smaller t equals a larger F.
why am i wrong?
to increase efficacy of an airbag for example, it's better to increase time of impact in order to reduce F on the driver.
Ok. Impulse is constant because momentum is fixed in that case. Momentum not fixed with tablecloth because you can transfer different amounts depending on what you do.
And then F is fixed so the only other thing to change is t to reduce p.
Thanks very much for your help.