1What is the working principle of the lever?
2Which work is the one done by the effort?
3Which one of these is not affected by friction: mechanical advantage, velocity ratio, or efficiency?
4Which of these statements are correct? (a) The ratio between load and effort when the lever is balanced is called the velocity ratio. (b) To lift a load greater than the effort, the effort must move further than the load. (c) Both mechanical advantage and velocity ratio have units. (d) Efficiency is the ratio of output work to input work, expressed as a percentage.
5Distinguish between mechanical advantage and velocity ratio.
6Distinguish between input work and output work.
7Give the reason why the efficiency of a lever is never a hundred percent.
8Give the reason why mechanical advantage is always less than velocity ratio.
9What is the work done when an effort is applied to a machine called?
10A lever 2 m long lifts a 900 N load with an effort of 300 N. If the fulcrum is 50 cm from the load, find its mechanical advantage, velocity ratio and efficiency.
11A machine is given 1500 J of input work and returns 1200 J of output work. What is its efficiency, and where did the rest of the work go?
12Why must the effort travel a longer distance when a small effort lifts a large load?
13The effort end of a lever goes down 2.4 m while the load rises only 0.6 m. What is the velocity ratio?
14If the fulcrum of a lever is oiled, which of the three changes: mechanical advantage, velocity ratio or efficiency?