An ideal machine is one whose efficiency is between 60 and 70 % between 70 and 8

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Question
An ideal machine is one whose efficiency is
Options
A. between 60 and 70 %
B. between 70 and 80%
C. between 80 and 90%
D. 100%

Correct Answer

100%

Engineering Mechanics problems

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2. The forces, which meet at one point and their lines of action also lie on the same plane, are known as
Options
A. coplaner concurrent forces
B. coplaner non-concurrent forces
C. non-coplaner concurrent forces
D. non-coplaner non-concurrent forces

5. Which of the following statement is incorrect?
Options
A. A force acting in the opposite direction to the motion of the body is called force of friction.
B. The ratio of the limiting friction to the normal reaction is called coefficient of friction.
C. A machine whose efficiency is 100% is known as an ideal machine.
D. The velocity ratio of a machine is the ratio of load lifted to the effort applied.

6. A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following:
Options
A. both the balls undergo an equal change in momentum
B. the change in momentum suffered by rubber ball is more than the lead ball
C. the change in momentum suffered by rubber ball is less than the lead ball
D. none of the above

7. According to lami's theorem
Options
A. the three forces must be equal
B. the three forces must be at 120� to each other
C. the three forces must be in equilibrium
D. if the three forces acting at a point are in equilibrium, then each force is proportional to the sine of the angle between the other two

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