Question

an effort of 65 N is applied to single fixed pulley to raise a load by 50 N by a height of 3 m. calculate the efficiency of the machine​

Answer 1

Answer:

Question 1

What is a fixed pulley? State its one use.

Solution 1

Fixed pulley: A pulley which has its axis of rotation fixed in position, is called a fixed pulley.

Single fixed pulley is used in lifting a small load like water bucket from the well.

Question 2

A single fixed pulley is used because it:

(a) Has a mechanical advantage greater than 1

(b) Has a velocity ratio less than 1

(c) Gives 100% efficiency

(d) Helps to apply the effort in a convenient direction.

Solution 2

It helps in applying effort in a convenient direction.

Explanation: A single fixed pulley though does not reduce the effort but helps in changing the direction of effort applied. As it is far easier to apply effort in downward direction, the single fixed pulley is widely used.

Explanation:

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Answer 2

Explanation:

Load to be lifted F

load

=50 kgf

Case 1 : Fixed pulley is used.

MA for single fixed pulley MA=1

Thus effort applied by the boy F

effort

=

MA

F

load

=

1

50

=50 Kgf

Case 2 : Movable pulley is used.

MA for movable pulley MA=2

Thus effort applied by the boy F

effort

=

MA

F

load

=

2

50

=25 Kgf

So, effort to be applied by the boy is less in case when he used a movable pulley because MA for a movable pulley is greater than 1.