Class 10 ICSE PHYSICS CH 3 Machine Question set 1

1.    What is Principle of Ideal Machine? Write Relation between MA and VR. 

2.    What Is MA and VR?

3.    Draw a diagram to show how a single pulley can be used so as to have its ideal MA=2.

4.    A type of a 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?

ANSWER:

 i) The pulley which is used in the arrangement is single fixed pulley.

ii) Single fixed pulley is used only to change the direction of the force applied.

5.    Name a machine which can be used to

i) multiply force

ii) change the direction of the force applied.

6.     i) Why is the mechanical advantage of a lever of the second order always greater than one?

        ii) Name the type of single pulley that has a mechanical advantage greater than one.

Answer : 

 i) The effort arm is always greater than the load arm so the mechanical advantage of class II lever is always greater than one.

ii) Single movable pulley is the type of the pulley whose mechanical advantage is greater than unity.

7.     i) With reference to the terms mechanical advantage, velocity ratio and efficiency of a machine, name the term that will not change for a machine of a given design.

ii) Define the term stated by you in pat(i).

Answer :

 i) Velocity ration will not change for a machine of a given design, because the distance moved by load in the same time is equal to the distance moved by the effort.

ii) Velocity ratio is defined as the ratio of the velocity of effort (VE) to the velocity of load (VL).

8.    Relation between MA, VR and efficiency?

9.    Give two reasons why the efficiency of a single movable pulley system is not 100%/.

Answer :

 In single movable pulley system, efficiency is not 100%, because

i) the weight of the movable pulley with its frame is not negligible as compared to the effort.

ii) the frictional force between the pulley wheel and the string used is not negligible.

iii) the string is not inextensible and massless.

10.    A pulley system has a velocity ratio of 4 and an efficiency of 90%. Calculate

i) the mechanical advantage of the system.

ii) the effort required to raise a load of 300 N by the system.

Answer : Given, Velocity ration VR = 4

Efficiency η = 90%

i) Mechanical advantage,

MA = VR x η100 = 4 x 90100 = 3.6    As η = MA/VR

ii) Effort E = ?, Load L = 300 N

11.    A cook uses a fire tong of length 29 cm to lift a piece of burning coal of mass 250 g. If he applies his effort at a distance of 7 cm from the fulcrum, what is the effort in SI unit?[Take g=10 m/s2]

12.   Can a machine be 100% efficient? Define why? 

13.    Name the device used as - a) Force Multiplier b) Speed Multiplier c) Change the direction

14.    Knife Belongs to Which class lever?

Answer : class 3

15.    Which class of lever rising a load by forearm?

Answer : class 3

16.    Lever in rising the weight of the body on teo?

Answer:  class 2

17.    Lever in the action nodding of head?

Answer: class 1

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