Reversible machine If a machine is capable of doing some work in the reversed direction, after the effort is removed, then the machine is known as reversible machine. The condition for a machine to be reversible is that its efficiency should be more than 50 %.
Non- reversible or self locking machine If a machine is not capable of doing some work in the reversed direction, after the effort is removed, then the machine is known as non-reversible or self locking machine. The condition for a machine to be non-reversible or self locking is that its efficiency should be less than 50 %.
55) For a self locking machine, the efficiency must be
Answer is:
less than 50 percent
Explanation:
Related Engineering Mechanics MCQ with Answers
Answer is:
The velocity ratio of a machine is the ratio of load lifted to the effort applied.
Explanation:
Velocity ratio of a machine is the ratio of load lifted to the effort applied.
Answer is:
second
Answer is:
increasing the length of the handle
Answer is:
equal to
Explanation:
A perfect frame is that which is composed of members just sufficient to keep it in equilibrium, when loaded, without any change in its shape. A perfect frame should satisfy the following expression:
n = 2j-3
where
n = Number of members, and
j = Number of joints.
An imperfect frame is one which does not satisfy the above equation (n = 2j — 3). The imperfect frame which has number of members (n) less than 2j – 3, is known as deficient frame. If the number of members are greater than 2j – 3, Then the imperfect frame is known redundant frame.