when i'm given ..
acceleration is 0.55 m/s^2
pushing force on a 1kg box is 3.14 N
fyi
the box is being pushed across the floor of an elevator that is moving up.
2007-12-17 05:59:45 · 4 answers · asked by mandm 2 in Science & Mathematics ➔ Physics
when i'm given ..
acceleration of elevator is 0.55 m/s^2
pushing force on a 1kg box is 3.14 N
fyi
the box is being pushed across the floor of an elevator that is moving up.
2007-12-17 06:15:49 · update #1
The moving elevator is in the problem just to make it tricky. If the elevator is moving up or down (or left or right) at a constant speed, it is the same as if it were not moving so there is no additional acceleration beyond gravity. I'm sure you can figure out the rest.
2007-12-17 06:06:28 · answer #1 · answered by John B 6 · 0⤊ 0⤋
F = ma = kN = kmg; so k = ma/mg = a/g; where F is the pushing force, k is the coefficient, m is the mass of the box, N is the normal weight = mg of the box pushing onto the floor. g = 9.81 m/sec^2 on Earth's surface.
As you can see k = a/g because the m's cancel out. Thus k is independent of the box's mass. You can do the math.
Note, the elevator moving up has no bearing on the problem if the elevator is moving up at a constant velocity. If the elevator is moving up with some acceleration, however, that will affect N because there will be an up down force added to N.
2007-12-17 06:14:12 · answer #2 · answered by oldprof 7 · 0⤊ 0⤋
I need to know what the acceleration refers to; is 0.55m/s^2 the acceleration of the elevator going up (if the elevator is accelerating upward, it effects the normal force acting on the block), or is that the acceleration of the block across the floor. if the elevator is moving up at a constant speed, that motion will have no effect on your answer, but if the elevator is accelerating upward, that changes the normal force and thus the frictional force. Without being sure of what accel refers to, I can't go too much further with the problem, sorry.
2007-12-17 06:10:10 · answer #3 · answered by kuiperbelt2003 7 · 0⤊ 0⤋
The equation you want is Fnet = m*a.
Fnet = F - Ff = F - µFn = F - µ*m*g = 3.14 - µ*1*9.8
So you now have
3.14 - µ*9.8 = 1*.55 which when solved for µ â
µ = .264
Unless the elevator is accelerating, it plays no part in this problem.
2007-12-17 06:15:32 · answer #4 · answered by Steve 7 · 0⤊ 0⤋