Phy231

Masses of 5 kg and 6 kg are suspended from opposite sides of a light frictionless pulley and are released.

What will be the net force on the 2-mass system and what will be the magnitude and direction of its acceleration?

answer/question/discussion: ->->->->->->->->->->->-> :

5kg*9.8m/s^2=49Newtons

6kg*9.8m/s^2=58.8Newtons

Fnet=58.8Newtons-49Newtons=9.8Newtons

#$&*

If you give the system a push so that at the instant of release the 5 kg object is descending at 1.8 meters / second, what

will be the speed and direction of motion of the 5 kg mass 1 second later?

answer/question/discussion: ->->->->->->->->->->->-> :

'dt=1s v0=1.8m/s

a=Fnet/m=9.8Newtons/11kg=.89m/s^2

vf=1.8m/s+.89m/s^2*1s=2.69m/s

'ds=v0'dt+.5adt^2=1.8m/s*1s+.5*.89m/s^2*1s^2=1.8m+.445m=2.245m

It's final velocity is 2.69m/s and it moved 2.245m in the direction of the lighter mass in 1s.

#$&*

During the first second, are the velocity and acceleration of the system in the same direction or in opposite directions,

and does the system slow down or speed up?

answer/question/discussion: ->->->->->->->->->->->-> :

In the same direction I believe because it was given an initial velocity. The velocity should eventually slow down because

the heavier mass will eventually win over and the system will start to move in it's direction.

15min

4/1/10 10:30am