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Physics homework help

The two masses are each initially 1.80m Above the ground. The Massless frictionless pulley is 3.2M above the ground when the system is released.

Small mass = 3.4 kg
Bigger mass = 3.5 kg

The acceleration of the system is 0.142m/s^2 which I found.

B. What is the Velocity of the heavier mass just before it hits the ground?

C. What maximum height does the lighter mass reach? Note: The lighter mass does not stop instantly when the heavier mass falls to the ground.

I need help on B and C. Would be helpful if you could show me how to do it, not necessarily give me the answer ^^.

January 22, 2013

7 Comments • Newest first

LowWillpower

For B and C you should do energy balance, not force analysis. We don't care about time.

Actually, for C you should just think about the question. I don't see any way the lighter mass would go further than the pulley, the string has a fixed length and it should just want to loop around.

Reply January 22, 2013 - edited
Watermelon

What's the answer for both questions? And what was the question for A?

I got
(this is getting censored for some reason)
35,316 m/s for B.

Reply January 22, 2013 - edited
Waccoo125

Tried changing gravitational potential energy of the he over mass onto kinetic to work out velocity?

Reply January 22, 2013 - edited
FrostyGun

[quote=foomps]I'm assuming gr.12 physic?

hint: do free body diagram for each of the masses[/quote]

Did those, lol. Still trying to figure out how to do the Velocity of the heavier mass

I tried doing vf^2 = Vo^2 + 2ad
Which gave me Vf^2 = 2(0.142)(1.80)
Vf = 0.714 M/s < not sure if I'm even correct

This is where I'm stuck. I'm not sure if I gotta use Acceleration of the system or some other one.

Reply January 22, 2013 - edited
FrostyGun

[quote=foomps]I'm assuming gr.12 physic?

hint: do free body diagram for each of the masses[/quote]

Mhm Grade 12 College Prep Physics.

Reply January 22, 2013 - edited
FrostyGun

[quote=BlackOpsII]So we wait until this late to post hw help? [/quote]

I've been doing homework for 4 hours now and finally got stuck. Which is why I'm asking now.

@Above I tried that and I feel like I'm still doing it wrong ahah xD.

Reply January 22, 2013 - edited
looklooklook

http://tuhsphysics.ttsd.k12.or.us/Tutorial/NewIBPS/PS4_8/PS4_8.htm

Reply January 22, 2013 - edited