A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave.
A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain.
The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991-1802 BCE) and Mesopotamia in the early 2nd millennium BCE. In Roman Egypt, Hero of Alexandria (c. 10-70 CE) identified the pulley as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another. Plutarch's Parallel Lives recounts a scene where Archimedes proved the effectiveness of compound pulleys and the block-and-tackle system by using one to pull a fully laden ship towards him as if it was gliding through water.
So I've been prepping for my Engineering Physics 1 final, and I've been having trouble with rotational motion problems, but this problem has been driving me crazy for the past two days:
Homework Statement
(I wanted to include a normal link to an image, but I'm a new member, so here's...
It is not actually homework, but a physics problem I have encountered. For ease of discussion, I am attaching the question [University Physics, Young and Freedman, 12th edition] and it's solution as appeared in the solutions manual.
What I don't understand is: In section (c), how can the...
Homework Statement
Hi all! I'm working on a dynamics homework and have hit a wall here:
"If the frictional moment at the pivot O is 2 N m, determine the angular acceleration of the grooved drum, which has a mass of 8 kg and a radius of gyration k = 225 mm.
Ans: α = 0.622 rad/s^2 "...
A pulley is mounted at the edge of a table.
A block is connected to an identical block through the pulley(assumed to be weightless)by a weightless in-extensible thread of length 2l. The left block rests on the table at a distance l from the edge (where the pulley is mounted) while the right...
Homework Statement
An assembly shown in the picture, GH , HK, HNL are three cables. the mass of box L is 52Kg,
a) determine the mass of box K in order to make angle theta as 25 degrees
Homework Equations
FX=0
FY=0
The Attempt at a Solution
right i started with
Fhn x...
A question has arisen (not homework) showing two pulley systems and a box being pulled up with a man pulling each. The question asks who has to pull hardest.
On one of them (A) the shafts (supporting the rope) are smaller whilst on the other (B) they are larger. The correct answer is that the...
Homework Statement
I have posted the snapshot.Homework Equations
I have written the distances from the datum line. Since we have two threads, I got two
equations.
2S_A +S_C=L_1
(S_B -S_C)+(h-S_C)=L_2
where L1 and L2 are the lengths of the strings excluding the
parts which remain constant in...
Homework Statement
An assembly shown in the picture, GH , HK, HNL are three cables. the mass of box L is 52Kg,
a) determine the mass of box K in order to make angle theta as 25 degrees
Homework Equations
Fx=0
Fy=0
The Attempt at a Solution
Fhn x cos(25) = Fhg x cos(0)
fhn x...
Homework Statement
Here is the diagram and I need to find a relationship between the acceleration in block A and the acceleration in block B.
http://dl.dropbox.com/u/64325990/HW%20Pictures/datum2.PNG
The Attempt at a Solution
Here is my diagram, which is wrong...
Homework Statement
An astronaut lands on a distant planet with an unknown gravitational field g’. On the bottom of his spaceship, he attaches an ideal frictionless pulley supported overhead with two light buckets hanging downwards, attached by a light rope. He places 24 kg of the same rock...
Homework Statement
Two masses, one of m_{1}= 3kg, the other of m_{2}=4kg, hang from opposite sides of a pulley of radius .15m. When released from rest, the heavier mass falls .34m in 4s. What is the rotational inertia of the pulley?
Homework Equations
Newton's second law and \tau =...
My zipline is 200 feet long built with 7/16" Stainless Steel Cable. Would 3/8" cable result in a faster ride with less noise from the trolley due to significantly less surface area for friction?
Homework Statement
A 1.53-kg mass hangs on a rope wrapped around a frictionless disk pulley of mass 7.07 kg and radius 66.0 cm. What is the acceleration of the mass?
I know this has been posted before but I learn better when I try to solve things on my own.
Homework Equations
F...
Homework Statement
http://imgur.com/ZkjXv
The given answers are (b) .309 m/s^2 (c) T1= 7.67N, T2=9.22N
Homework Equations
I_disc = .5(mass_disc)r^2
Sum of Torque = I α
a = r α
The Attempt at a Solution
We will define the system moving right and down as positive to get a positive...
A motor can't lift a pale of water for given diameter of pulley. (consider the motor directly connected to the pulley). So, the diameter of the pulley should be Increased or decreased? Why?
Homework Statement
A block of mass m=2.4kg is attached to a string that is wrapped around the circumference of a wheel of radius r=7.6cm. The wheel rotates freely about it's axis and the string wraps around it's circumfrence without slipping. Initially, the wheel rotates with an angular...
Two blocks of mass m connected by a light string passing over a pulley.
Say, one of the blocks is pushed downwards with a force F and it attains velocity v.So the other block moves upwards with the same speed v right?
Total moementum = mv - mv = 0( because one is moving upwards and other...
Homework Statement
1) an aluminium wire, of length L1 = 60.0 cm, cross sectional area 1.00 x 10^-2 cm^2, and density 2.60 g/cm^3, is joined to a steel wire of length L2, of density 7.80 g/cm^3 and the same cross sectional area. The compound wire, loaded with a block of mass m = 10.0 kg, is...
Homework Statement
m(1) is 20kg
m(2) is 30kg
gravity use 10
U static is .6
u kinetic is .4
Homework Equations
Basically my professor gave the answer to the question in the link along with the picture. The only problem is that i am not sure he did case three right and i am after...
Homework Statement
http://data.imagup.com/10/1146555432.jpg
Homework Equations
Force applied on the weight=F*(MA).
The Attempt at a Solution
i chosse the E system ...it has the greater mechanical advantage (MA)=3.
MA(of A)=1, MA(of B)=2,MA(C)=2,MA(D)=2,MA(E)=3..
I hope my...
Homework Statement
A system comprised blocks, a light frictionless pulley, and connecting ropes is shown in the figure. The 9.0-kg block is on a perfectly smooth horizontal table. The surfaces of the 12-kg block are rough, with \mu_k = 0.30 between the block and the table. If the 5.0-kg...
In this problem they show a diagram of a pulley system with an inclined plane (25 degree incline). There is a box called m1=47kg resting on the incline plane and m1=35kg hanging on the vertical line. The question reads: The coefficient of friction between m1 and the surfvace of the inclined...
Homework Statement
Calculate the tension in the cable connecting the two masses. Assume all surfaces are frictionless.
in lieu of the picture here are the given specs:
on the left side a 5 kg mass with a 60' incline
on the right side a 6 kg mass with a 70'incline
Homework Equations...
Homework Statement
Two blocks are connected by a string that goes over an ideal pulley as shown in the figure and pulls on block A parallel to the surface of the plane. Block A has a mass of 3.00 kg and can slide along a rough plane inclined 30.0° to the horizontal. The coefficient of static...
If there is a problem like in the image provided, and the rope has a mass but the pulley is not being considered in the problem, what forces would the rope affect the man with?
Since the rope touches the ground will the rope send a normal force up which pushes the man up? I am assuming that...
Homework Statement
You are pulling on a rope attached to the outer radius of a pulley with a moment of inertia I=676 kgm2 as shown. The tension in the rope that you are pulling is 477.9 N. A pack of mass 30.8 kg is attached to the pulley's inner radius as shown. If the inner radius of the...
Homework Statement
I have 2 blocks. M1 is resting on a horizontal plane and attached to a string that goes over a pulley to M2. The plane is like an air hockey table to simulate very little friction. I attached spark tape to M1 so I could measure the time it took and distance traveled. Now...
Homework Statement
To make it easier on the people who will try to help me, I've scanned the problem:
We are interested in finding the following variables:
Angles a and c
The tension between A and B (TAB)
Homework Equations
The pulley is a "perfect pulley" no friction
The system...
Determine the speed of the elevator if each
motor draws in the cable with a constant speed of 5 m>s.
Here is a link to the question and diagram. Scroll down to page 154. Its question 12-199.
http://www.mem.odu.edu/~bawab/ME205f/hwk12.pdf
I don't understand how to get the distances. Any...
RPM to Pulley Question Please Help Thanks!
I have a log splitter that uses a gas engine 3600 RPM the drive pulley is 1.5"OD diameter and the driven pulley is 18.25" diameter (Super Splitter is the brand name) So from what i calculated was the driven pulley weighs in at 75lbs and spins at about...
Homework Statement
Blocks A and B have masses 11 kg and 5 kg, respectively, and they are both at a height h = 2m above the ground when the system is released from rest. Just before hitting the ground block A is moving at a speed of 3 m/s. Determine a.) the amount of energy dissipated in...
Homework Statement
The system shown is at rest when a constant 250N force is applied to block A. Neglecting masses of pulleys and friction, determine:
a) Velocity of block B after block A moved 2 m.
b) The tension in the cable
http://imageshack.us/photo/my-images/259/photoivl.jpg/...
I need to calculate the work done by an electric motor when it has a pulley wheel on the end but nothing on the pulley wheel. I know work done = force x distance. And of course force = mass x acceleration. But I cannot for the life of me think of how I am going to work out the acceleration? or...
Homework Statement
A block with mass, m1 = 5.5 kg rests on the surface of a horizontal table which has a coefficient of static friction of μs = 0.52. This block is connected to another block by a pulley system and it hangs vertically under the influence of gravity, g. The hanging block has...
Homework Statement
A car and pulley system are setup as shown. Find the acceleration of the car. The car wheels have a friction coefficient of 0.15. The car has a mass of 0.05 kg while the block has a mass of 0.02 kg.
http://sadpanda.us/images/836771-GBD7SB9.jpg
*sorry if the picture is bad I...
Homework Statement
The slippage of flexible belts over shafts or pulleys of circular cross sections is an important consideration in many mechanical devices. When the frictional contact between the belt and the shaft is about to be broken (that is when the slippage is imminent), a belt drive...
Homework Statement
Two blocks of mass m1 and m2, resting on a frictionless tabletop, are connected by a massless string passing through a frictionless pulley of mass mp. The figure shows a top view of the arrangement. If a force of magnitude F is applied to the pulley in the direction...
Homework Statement
Three objects with masses m1 = 37.5 kg, m2 = 19.5 kg, and m3 = 11.1 kg are hanging from ropes that are redirected over pulleys. What is the acceleration of m1? Negative numbers for downward, and positive numbers for upward, please.
There should be a diagram of what the...
I need to calculate how much tension it would require to bend large insulated cable of various sizes around a pulley. The Conductor would be made of aluminum or copper and solid. The Insulation would be of various thicknesses depending on the cable. I was looking at breeaking this problem down...
Homework Statement
m1 and m2 are connected by a massless string wrapped around a massless pulley. An external force F is applied to the pulley. m1 does not equal m2
find the acceleration of each mass, the tension in the string, and the acceleration of the pulley.
F external and m1 and...
Homework Statement
This is a "DOE" (Design of Experiment) problem. Basically, the construction is fairly simple. 3 pulleys, 2 on either side, and a free pulley with a weight suspended on it in the middle. Picture is available (don't mind my crappy paint skills, rope lengths are all...
Hey..
This is a question I received as part of my homework
Your great grandmother gave you an antique scale that her great grandmother gave to her. It consists of a square platform mounted on 4 identical
springs. When you step on the platform, you compress the springs, causing
the platform...
Homework Statement
Attached is the picture of the problem and my free body diagram.
The system is in equilibrium.
Homework Equations
Fy = 0 Fx = 0
The Attempt at a Solution
I'm having trouble solving the two equations that I arrive with...
I use +x to the right, and +y up...
Homework Statement
2 masses m1=50g and m2=5g are connected as shown (sori walang pci) m1 is free to move along a horizontal frictionless table. Neglecting the mass of the cord connecting the two masses and assuming a frictionless pulley. Determine the accelereation of the system of blocks...
Can a man whose weight is 50KG (but powerful arms) lift another man with 70 KG weight using an overhead pulley.
I guess no since the light man is not clamped to the groud, his arm strength will not bear any significance and he can lift only the wieght(on other side of the pulley) equal to his...
1. Homework Statement
Two particles of masses m1=8 kg and m2=5 kg are connected to the two ends of a light inextensible string which passes over a fixed smooth pulley. Initially each of the two particles are held at a position which is 5 m above a horizontal ground. The objects are then...
Homework Statement
I'm on my last question for my coursework and this is it.
I have managed to find out how to calculate the efficiency of a pulley but not "what is the efficiency of a pulley"
Could someone please help me.
Homework Equations
Efficiency = (Mechanical Advantage /...
Homework Statement
A pulley system has an efficiency of 71.5 percent. How much of the rope must be pulled in if a force of 641 N is needed to lift a 160 kg desk 2.51 meters?
Homework Equations
IMA = De/Dr
MA = Fr/Fe
Efficiency (%) = Wo/Wi
Efficiency (%) = MA/IMA
I have absolutely...
(see image)
How do I go about this?
since a1 is larger, and the two trucks are around the pulley, then a2 is opposing (to some extent) so i thought the answer would be a1-a2? but I checked the answer and it's a1+a2/2
please help
thank you :)