MACHINES 1

In a speed multiplier

• effort < load

• effort > load

• effort = load

• VR > 1

Which of the following statement about machines is not true:

• It can increase magnitude of force

• It can increase speed

• Its output is greater than input

• It can change the direction of force.

In a practical machine

• MA < VR

• efficiency = 1

• MA > VR

• Output = Input

If de and dl is distance moved by effort and load respectively and E and L is effort and load, then velocity ratio VR =

• de/dl

• dl/de

• L/E

• E/L

The unit of mechanical advantage and velocity ratio is :

• N, m/s

• m, m/s

• N, no unit

• no unit, no unit

A machine is driven by an effort of 100 kgf and is able to lift a 500 kgf load. Its MA is

• 5

• 0.2

• 50000

• 1

• 1000 J

• 10000 J

• 50000 J

• 5000 J

A machine of VR = 3 has an efficiency of 60 percent. Its MA =

• 180

• 20

• 1.8

• 0.2

For an ideal machine,

• MA = 1

• efficiency = 1

• VR = 1

• efficiency = 0.1

In actual machines :

• VR increases

• VR decreases

• MA remains same

• VR remains same