Karteikarten
Unit 1.1 : Machines around us
Karten in diesem Stapel (20)
- 1What do simple machines do?Simple machines change the size, direction or speed of a force to make a job easier.
- 2How can simple machines make tasks easier?Simple machines make tasks easier in 3 different ways. It can -:
-Change the size of a force
-Make things speed up
-Change the direction of a force
- 3What are effort and load?To get a job done, you apply a force called an effort. The load is the force actually required to do the job.
- 4Why do we use force multiplier frequently?Machines used in this way magnify the force you apply to do a job, making the task easier and the effort required smaller.
- 5What is the useful reason for using speed multipliers?We use speed multipliers when we want to produce a large amount of a load while applying a small amount of effort.
- 6How can a machine change the directions in which a force acts?Using a pulley, you pull the cables down and a pulley changes the direction of the force on the blinds to lift them up.
- 7How do levers make the jobs easier?A lever, which is a simple long rigid stick (like a crowbar), increases the size of the effort that you can apply or reduces the effort needed, making the jobs easier.Therefore, the lever increases the force that you can apply.
- 8Give an example of when a lever becomes a useful material in some cases.Using the claw of a hammer to pull a nail out of a wood, the hammer acts as a lever which reduces the size of the effort needed to pull out the nail.This makes the task much easier than doing it with your hand.
- 9How can you measure how much easier a task became?You can measure how much easier a task has become by calculating the mechanical advantage a machine produces.
- 10What does a machine with a mechanical advantage allow you to do?It allows you to -:
-Lift twice the load you would probably be able to lift
-use half the force you would have otherwise needed to do a particular job.
- 11A worker applies an effort of 100N to lift a rock of weight 300N using a wheelbarrow. Calculate the mechanical advantage of the wheelbarrow.
- 12Why is it easier to open a tin with a longer screwdriver?It is easier to open a tin using a longer screwdriver because it has a greater distance from the fulcrum to the effort.
- 13What does the principle of levers rule states about calculating mechanical advantage?
- 14What is the formula used to calculate the mechanical advantage for a lever?
- 15What are the three different types of levers?
- 16What is the first-class lever?A first-class lever has its fulcrum positioned between the effort and the load.These levers act as a force multipliers.The greater the distance between the fulcrum and the effort, the greater the mechanical advantage of the lever.
- 17What is second-class lever?A second-class lever has the fulcrum located at one end, the effort at other end and load in the centre.
- 18What is a third-class lever?A third-class lever has the fulcrum located at one end, with the load at the other and effort in the centre.
- 19Classify the following as first, second or third class lever <-----------A wheelbarrow is an example
of a second-class lever.
- 20—A scissor is an example of
a first-class lever.