M.A and V.R

Which of these affects the efficiency of a machine?

• Energy

• friction

• load

• frequency of use

The Mechanical advantage of a good machine is greater than 1

• True

• false

• It is always 1

• none of the above

Mechanical advantage is calculated from:

• Load x effort

• load + effort

• load /effort

• effort/load

Calculate the mechanical advantage of a machine which needs an effort 5 N to lift a load of 55 N

• 11

• 11 N

• 60

• 220 N

An effort of 5.5 N is applied to a machine with MA of 4. What is the load that would be lifted?

• 1.5 N

• 9.5 N

• 22 N

• 55 N

A machine requires an effort of 2.5 N which moves through a distance of 45 cm to lift a load through 9 cm. Calculate the velocity ratio of the machine

• 2.5

• 5

• 9

• 36

The velocity ratio of a machine is 125. If it moves a load through a distance of 4m, calculate the distance moved by the effort

• 129 cm

• 121 m

• 400 cm

• 500 m

The MA of a machine is 9 and the VR is 12. Calculate its efficiency

• 25 %

• 50 %

• 75 %

• 100 %

A machine uses a force of 3N to lift a load of 18 N. This force moves through 80 cm while the load is lifted through 10 cm. Calculate the efficiency of the machine

• 30 %

• 50 %

• 60 %

• 75 %

One of these is needed to maintain a machine

• Allowing enough sunshine on it

• exposing it to rain to that it can become cool

• lubricating it

• dismantling it when not in use