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121.

The maximum mechanical advantage of a lifting machine is

A.	1 + m	B.	1 - m
C.	1 / m	D.	m

122.

The maximum efficiency of a lifting machine is

A.	1 / m	B.	V.R. / m
C.	m / V.R.	D.	1 / m x V.R.

123.

The velocity ratio for the first system of pulleys is. Where n is the number of pulleys.

A.	n	B.	n2
C.	2n	D.	2n - 1

124.

The velocity ratio for the second system of pulleys is n.

True

False

125.

The velocity ratio for the third system of pulleys is

A.	n	B.	n2
C.	2n	D.	2n - 1

126.

Which of the following statement is wrong?

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.

127.

The velocity ratio of a first system of pulleys with 4 pulleys is

A.	4	B.	8
C.	16	D.	20

128.

If the number of pulleys in a system is equal to its velocity ratio, then it is a

A.	first	B.	second
C.	third

129.

The velocity ratio of a simple wheel and axle with D and d as the diameters of effort wheel and load axle, is

A.	D + d	B.	D - d
C.	D x d	D.	D / d

130.

The velocity ratio of a single purchase crab winch can be increased by

A.	increasing the length of the handle	B.	increasing the radius of the load drum
C.	increasing the number of teeth of the pinion	D.	all of the above