The Movable Pulley

Q.

What is the single movable pulley ? What is its mechanical advantage in the ideal case ?

Q.

The hinges of the door produce a squeaking sound. Explain?

Q. What is d2sp3 hybridization?

Q.

Draw a labelled diagram of an arrangement of two pulleys, one fixed and other movable. In the diagram, mark the directions of all forces acting on it. What is the ideal mechanical advantage of the system? How can it be achieved?

Q.

A movable pulley is used as :

(a) a force multiplier

(b) a speed multiplier

(c) a device to change the direction of effort

(d) an energy multiplier

Q.

Differentiate between a single fixed pulley and a single movable pulley.

Q.

State four differences between a single fixed pulley and a single movable pulley.

Q. Calculate the mechanical advantage and velocity ratio if there are 2 movable pulleys and one fixed pulley arrangement system.

Q.

Name the type of a single pulley that has an ideal mechanical advantage equal to 2. Draw a labelled diagram of the pulley mentioned by you.

Q.

A pulley system has a velocity ratio 3 and an efficiency of $80\%$. Draw a labelled diagram of this pulley system. Calculate :

(a) the mechanical advantage of the system, and

(b) the effort required to raise a load of 300 N.

Q. What is Krolls process?

Q.

From the diagram given below, what effort has to be applied at C to just raise the Load L = 20 Kg?
(Neglect the weight of pulley A and friction)

1. 10 kgf

2. 15 kgf

3. 20 kgf

4. 30 kgf

Q.

Give two examples of when a machine is used to gain speed.

Q.

Under what conditions is the work done i) maximum and ii) minimum?

1. i) When force and displacement are parallel to each other and ii) When force and displacement are at 180⁰ to each other.

2. i) When force and displacement are parallel to each other and ii) When force and displacement are at perpendicular to each other.

3. i) When force and displacement are perpendicular to each other and ii) When force and displacement are parallel to each other.

4. i) When force and displacement are at 180⁰ to each other and ii) When force and displacement are parallel to each other.

5. i) When force and displacement are at 45⁰ to each other and ii) When force and displacement are perpendicular to each other.

Q. Hunds rule

Q.

A pulley system has velocity ratio of 3. If it efficiency is 75%, calculate the maximum load it can raise using an effort of 30 N. [Assume 1 kgf = 10N, 1 gf = 1000 dynes]

1. 67.5N

2. 70N

3. 60N

4. 65N

Q. The mechanical advantage of an ideal single fixed pulley is and of an ideal single movable pulley is .

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

Q.

What is the mechanical advantage of a single movable pulley in the ideal case?

1. less than 1

2. equal to 1

3. 2

4. less than 2

Q. A bucket of water weighing $6\text{N}$ needs to be lifted through a single movable pulley system by a boy. How much effort should he apply to pull the bucket up if the pulley system has an efficiency of $75\%$?

1. $9\text{N}$
2. $4\text{N}$
3. $6\text{N}$
4. $10\text{N}$

Q.

The mechanical advantage of an ideal single movable pulley is :

(a) 1 (b) 2

(c) less than 2 (d) less than 1.

Q.

A pulley system has velocity ratio of 3. If it efficiency is 75%, calculate its mechanical advantage. [Assume 1 kgf = 10N, 1 gf = 1000 dynes]

1. 2.25

2. 4.0

3. 1.5

4. 2.5

Q. Hybridisation technique

Q.

A simple machine is made up of many smaller machines.

1. True
2. False

Q.

In a single movable pulley system, a load of 225 kgf is lifted by an effort of 75 kgf. Velocity ratio of the single movable pulley is 4. Find the percentage efficiency of the system.

1. 50%

2. 0%

3. 75%

4. 100%

Q.

You use a lever with a mechanical advantage of 30. How heavy a load can you lift with an effort of 100 N?

Q.

What is the single movable pulley ? What is its mechanical advantage in the ideal case ?

Q.

A block and tackle system has 5 pulleys. If an effort of 1250 N is needed in the downward direction to raise a load of 5000 N calculate(a) M.A. (b) V.R.(c)efficiency of the system. Also find the magnitude of extra force needed to overcome the friction.

Q.

What do you understand by simple machines?

Q. Integration on tanz

Q.

Give two reasons why the efficiency of a single movable pulley is not $100\%$.