Multiple Movable Pulley

Q.

Draw a diagram of combination of three movable pulleys and one fixed pulley to lift up a load. In the diagram, show the directions of load, effort and tensiom in each strand. Find : (i) the mechanical advantage , (ii) the velocity ratio, and (iii) the efficiency of the combination, in the ideal situation.

Q.

A pulley system has a velocity ratio of 4 and an efficiency of 90 %. The effort required to raise a load of 300 N by the system is

1. 83.33N

2. 500.22N

3. 75.66N

4. 90.88N

Q.

In operating a water pump a resistance of 480 N Is overcome by an effort of 72 N. If the distance of the fulcrum from the point where resistance acts is 0.2 m find the distance from the fulcrum, where effort is applied.

Q.

The diagram alongside shows an arrangement of three pulleys A, B and C. The load is marked as L and the effort as E.

(a) Name the pulleys A, B and C.

(b) Mark in the diagram the directions of load (L) effort (E) and tension $T_1$ and $T_2$ in the two strings.

(c) How are the magnitudes of L and E related to the tension $T_1$?

(d) Calculate the mechanical advantage and velocity ratio of the arrangement.

(e) What assumptions have you made in parts (c) and (d)?

Q.

According to the “law of levers”, $load\times loadarm=effort\times effortarm$.

1. True
2. False

Q.

The figure shows a diagram of a system of four pulleys. The upper two pulleys are fixed and the lower two are movable. What are the mechanical advantage and velocity ratio of the system?

1. M.A. = 5

2. M.A = 2

3. V.R = 2

4. V.R = 4

Q.

Define the term Lever

Q.

A system of pulleys is used to lift a load of $1000k{g}_{wt}$. If the efficiency of the pulley system is $80\%$ and velocity ratio is $20$, find the effort required to lift the load.

Q.

A pulley system has velocity ratio of 3. If it efficiency is 75%, calculate the distance by which the load is raised, if the effort pulls in 12 m of rope.

1. 4 m

2. 36 m

3. 5 m

4. 3 m

Q.

The SI unit of a work is Newton

1. True
2. False

Q.

A fulcrum divides a crowbar in the ratio $3:1$. What weight will be lifted if an effort of $100\mathrm{N}$ is applied at the end of its long arm?

1. $400\mathrm{N}$

2. $100\mathrm{N}$

3. $300\mathrm{N}$

4. $500\mathrm{N}$

Q. A block and tackle system has $5$ pulleys. If an effort of $1000N$ is needed in the downward direction to raise a load of $4500N$. Calculate the efficiency of the system.

1. $50\%$
2. $60\%$
3. $90\%$
4. $80\%$

Q.

What happens when mechanical advantage (MA) becomes equal to one?

Q.

A pulley system can lift a load of 1200 N by an effort of 250 N. If the resistance due to the weight of movable parts and friction is 300 N. Find the total number of pulleys in the system.

1. 2

2. 4

3. 6

4. 8

Q.

A boy uses a single movable pulley to lift a load of $50\mathrm{kgf}$ to some height. Another boy uses a single fixed pulley to lift the same load to the same height. The ratio of efforts on single movable pulley to efforts on single fixed pulley is,

1. $2$

2. $1$

3. $\frac{1}{2}$

4. $4$

Q.

State the usefulness of such a machine whose mechanical advantage is less than $1$.

Q. A pulley system has a single fixed pulley and a single movable pulley. Find out its mechanical advantage.

1. 1
2. 2
3. 3
4. 4

Q. A type of single pulley is very often used as a machine even though it does not give any gain in mechanical advantage.
(i) Name the type of pulley used.
(ii) For what purpose is such a pulley used?

Q.

A ________ has length and width, but no height, and extends infinitely on all sides.

Q. Fig 3.40 shows a block and tackle system of pulleys used to lift a load.
What is the mechanical advantage of the system ?

Q. A block and tackle system has a velocity ratio of $4$. If a man can exert a pull of $240\text{kgf}$, what is the maximum load he can raise with this pulley system if its efficiency is $80\%$? Also, determine the number of pulleys used in the system.

1. $768\text{kgf};4$
2. $480\text{kgf};5$
3. $112\text{kgf};6$
4. $960\text{kgf};4$

Q. A block and tackle system has $5$ pulleys. If an effort of $1000N$ is needed in the downward direction to raise a load of $4500N$. What is the mechanical advantage ?

1. $4.5$
2. $2$
3. $3.5$
4. $5$

Q. Draw a diagram to show a block and tackle pulley system having a velocity ratio of $3$ marking the direction of load(L), effort(E) and tension(T).

Q. what is the velocity ratio of the pulley?

Q. A spanner with a longer handle can tighten nuts and bolts with less effort.

1. True
2. False

Q.

A block and tackle system has 5 pulleys and is 90% efficient. If the effort required to lift a load is 1000 N, find the effort required.

1. 2000 N

2. 100 N

3. 111.1 N

4. 155.5 N

Q. A lever has a mechanical advantage of 10. What load is newtons, can be moved by an effort of 6 newtons.

Q. The given combination of pulleys is used to lift a load of $2000\text{N}$. Find the distance traveled by the pulley $\text{B}$ if the effort moves by $1\text{m}$.

1. $0.10\text{m}$
2. $0.25\text{m}$
3. $0.50\text{m}$
4. $0.60\text{m}$

Q. In the system of pulleys shown what should be value of $m_1$ such that 100 gm remains at rest : $(Takeg=10{m/s}^2)$

1. $180gm$
2. $100gm$
3. $160gm$
4. $200gm$

Q. A fixed and movable pulley system has $50\%$ efficiency. Find the velocity ratio of the system.

1. $2^4$
2. $2^2$
3. $2^5$
4. $2^3$