Max Mass Dresser Liftable w/ 150N Force - 46kg

  • Thread starter Thread starter gmichel395
  • Start date Start date
  • Tags Tags
    Mass
AI Thread Summary
The discussion revolves around calculating the maximum mass of a dresser that can be lifted using a pulley system with a force of 150N. Participants analyze the number of rope sections supporting the load, initially miscounting but ultimately agreeing on six sections. Using the formula for tension, they conclude that the effective lifting force is 900N (6 sections x 150N). Dividing this by the acceleration due to gravity results in a maximum mass of approximately 92kg. The final consensus is that the closest answer to the maximum mass of the dresser is 92kg.
gmichel395
Messages
10
Reaction score
0

Homework Statement


"Using the pulley system shown to lift the heavy dresser, the person is applying a force of 150N to the end of the rope. Which of the following is closest to the maximum mass of the dresser that can be lifted with this force? [Ignore weight & friction from pulleys/rope.]"

A) 46kg
B) 92kg
C) 110kg
D) 150kg
E) 180kg

20160401_203844~2[1].jpg
2. Homework Equations

Newton's 2nd & 3rd laws

The Attempt at a Solution


So she's pulling with 150 N and there are three pulleys connected to the dresser, so her effort is tripled. 450N lifts the dresser and so the mass is 46kg?
 
Physics news on Phys.org
Label each section of the rope with its tension. How many sections of rope are supporting the dresser?
 
I count six sections plus the one the girl is holding so seven. 7*150 divided by g gives approximately 110kg?
 
gmichel395 said:
I count six sections plus the one the girl is holding so seven. 7*150 divided by g gives approximately 110kg?
The one the girl is holding is holding the girl...not the dresser. So one less. You want to count only the ropes that are directly supporting the load.
 
Ah so six. And the answer is 92kg?
 
gmichel395 said:
Ah so six. And the answer is 92kg?
Yes.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top