The coefficient of kinetic friction between the surface of the incline plane and the a 2 kg mass is equal to .7 kinetic friction for another mass connected mass of 3 kg the kinetic friction is .6 (These two masses are connected by a cable) If the two masses are to accelerate at 3.5 m/s^2, in the the upward direction at an angle of 35 degrees from horizontal.
What force is necessary to accomplish this acceleration up the incline plane? If the 2 kg mass starts at the bottom of the incline.
How far up the incline will the masses have moved in 4 seconds?
What will the velocity of the 3 kg mass at 4 seconds be? The cable does not stretch!!
2006-10-14 11:28:04 · 6 answers · asked by Shane W 1 in Science & Mathematics ➔ Physics
draw a picture (otherwise known as a free-body diagram). gravity is acting on both objects, and it pulls in the downward direction. these blocks push downward on the ramp because of gravity, and because of newton's 3rd law, the ramp reacts by exerting a normal force on the blocks, which goes perpendicular to the plane of the ramp. the normal force has to counteract the component of gravity that's going perpendicular to the ramp (in this case, mgsin(35). the blocks are also being acted on by friction, which goes opposite to the direction of motion (in other words, down the ramp) and has a magnitude equal to the coefficient of friction times the magnitude of the normal force. since there are two masses, the total force needed is equal to the sum of the forces for each mass. also, to calculate the total friction force, just add the individual friction forces. the total force must counteract the total friction AND accelerate the objects by 3.5 m/s/s (here, use the sum of the masses for the total mass).
for the positions and velocities, just use kinematics:
v=v0+at
x=x0+v0t+.5at^2
where v is the velocity at any time t, x is the position at any time t, v0 is the initial velocity, x0 is the initial position, and a is the acceleration. don't be thrown up by the fact that the ramp is inclined; you can always rotate your axis.
2006-10-14 11:52:20 · answer #1 · answered by Ramesh S 2 · 0⤊ 0⤋
Start by defining which direction is forward and which direction is backward as related to the cable. Apply this direction to all objects that contact the cable. Now imagine that the cable is totally flat and straight and draw your force diagrams for each mass using your above positive/negative directions. Don't forget to include your normal force relative to the inclined plane. Add up all of the forces in the positive direction, and add up all of the forces in the negative direction to find the net force on the objects you're interested in. Then the rest should be pretty easy from there. The key to force models is setting it up correctly. Good luck!
2006-10-14 11:38:21 · answer #2 · answered by ohmneo 3 · 0⤊ 0⤋
It's actually fairly straightforward. Resolve the weight vectors into friction vectors (parallel to the slope) and pressure vectors (perpendicular to the slope), and you can use the coefficient of friction to calculate the friction vector arising from the friction. With some addition of components, it will all work out.
2006-10-14 11:34:15 · answer #3 · answered by Anonymous · 0⤊ 0⤋
do your own homework. if you search online, the necessary equations will be available
2006-10-14 11:31:13 · answer #4 · answered by Anonymous · 0⤊ 0⤋
http://en.wikipedia.org/wiki/Coefficient_of_friction
2006-10-16 17:42:24 · answer #5 · answered by Surya M. 3 · 0⤊ 0⤋
No
2006-10-14 11:35:16 · answer #6 · answered by The Foosaaaah 7 · 0⤊ 0⤋