You push a 25kg wooden box across a wooden floor at a constant speed of 1 m/s. The kinetic coefficient of friction between the crate and floor is .20. How much force do you exert on the box?
I was out for a few days... and I have no idea how to find the answer.
2006-11-07 10:27:13 · 2 answers · asked by Jer G 3 in Science & Mathematics ➔ Physics
F - Ff = m*a
This is because the force you're applying is in one direction, while the frictional force is ALWAYS in the opposite direction. Frictional forces act to prevent the applied movement.
Because you're moving at constant velocity, you therefore have no acceleration, so:
F - Ff = 0
-or-
F = Ff
Ff is the force due to friction which:
Ff = u * Fn
Where "u" (it's actually the greek letter mu, but this will do) is equal to the coefficient of friction, and Fn is equal to the perpendicular force acting on the box. On flat ground, the normal force is equal to the gravitational force, but on inclines you have to break it up into its vector components.
F = u*Fg
F = (0.20)*(25kg)*(9.8m/s^2)
F = 49N
You see that the velocity at which you push it has no bearing on the answer because neither your applied force nor frictional forces are due to constant velocities.
2006-11-07 10:34:10 · answer #1 · answered by sft2hrdtco 4 · 0⤊ 0⤋
i found out how to find kinetic energy then the froce but i need the distance so if you have it e-mail it to me but if it is no where near what you are looking for sorry
2006-11-07 18:36:18 · answer #2 · answered by princess-of-somany 3 · 0⤊ 0⤋