# Simple Machines

## Students’ Learning Outcomes

·         What is the simple machine?
·         Demonstrate how wedge and incline plane are used to move the objects.
·         Compare the three kinds of levers using example.
·         Describe how lever makes work easier by giving examples of its uses from daily life.

### Information for Teachers

·         Simple machines makes work easier for us by allowing us to push or pull over increased distanced.
·         There are 6 basic simple machines; the lever, the wheel and axle, the inclined plane, the wedge, the pulley, and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work. But what is work? Work is the amount of energy necessary to move an object.

·         An inclined plane is a slope or a ramp along which a load can be lifted up easily. Its examples are gate entrance ramps, ladder and parking ramp etc.
·         Two inclined planes joined together from a wedge. It can be used to cut an object into two portions and lift an object e. g. knife, axe, nail, pin, sledge hammer and knitting needles etc.
·         The Lever are simple machines used to lift heavy objects with less effort around a pivot (fulcrum).
·         The lever turns about a fixed point called fulcrum (F) when a force called Effort € is applied to overcome a resisting force known as load(L)
·         In the first kind of levers, the fulcrum is between the effort and the load e.g. a pair of scissors, pliers, a lid opener and claw hammer etc.
·         In the second kind of levers, the load is between the fulcrum and effort e.g. Nut cracker, bottle opener, wheelbarrow and paper cutter etc.

·         In the third kind of levers, the effort is between the fulcrum and load e.g. a pair of tongs, a stapler, broom and human arm etc.

### Material / Resources

Books, wooden plate, spring balance, thread, knife, steel ruler, apple, meter rod, weights, wedge, textbook.

#### Worm up Activity

·         Ask the students what is a simple machine?
(Students’ response: A device which makes work easier to do)
·         Ask the students to name some simple machines you often use in daily life.
·         Make a list of these on the board
(Students’ response: Knife, pair of scissors, tongs, screw, driver, plier and hammer etc.

Development

#### Activity 1

·         Ask a student to lift a bundle of books tied with the spring balance vertically upward.
·         Ask him / her to measure the weight of bundle by noting the reading of spring balance.
·         Then ask him / her to make an inclined plane by using a stack of books and wooden plate. Tie a bundle of books with one end of the thread. Attach the other end of the thread with a spring balance and pull the bundle along the inclined plane.
·         Ask the student to note the reading of the spring balance.
·         (students, response: The reading when books tied with the spring balance are pulled along the inclined)
·         Why the reading is less in the second case? (students’ response: Less force is required to pull the same load along an inclined plane)
·         Ask which will be easier; moving the books using the inclined plane or moving them by lifting straight up and why?
(Students’ response: Moving the books along inclined plane is easier inclined plane is a simple machine which makes it easier to lift the things to a height)
·         Ask students to give different examples of inclined plane?
(Students’ response: Gate entrance ramp, car ramps and parking ramp etc.

#### Activity 2

·         Ask a student to cut an apple with help of a ruler
·         Ask does ruler cut the apple easily?
(Students, response: No.)
·         Now ask the student to cut the apple with the help of a knife.
·         Ask the students, is it cut easily with knife?
(Students’ response: Yes, because things can be cut easily with the help of a wedge.
·         Inform them that knife is also a simple machine called wedge.
·         Ask them what is the difference in the construction of a ruler and a knife?
(Students’ response: One edge of knife is very sharp and thin which gradually goes on becoming thicker. Since it is formed by joining two inclined planes, so it is called a wedge. Ruler has both edges equally thick)
·         Ask students to give some other examples of wedges?
(Students’ response: Axe, nail, pin, sledge hammer and knitting needles etc)

#### Activity 3

·         Prepare a lever by balancing a meter rod as its centre of gravity C on a wooden wedge. Hang a weight of 100g at one side of the ruler.
·         Ask a student what happened?
(Students’ response: the weight tends to pull the rod downward on that side)
·         Now hang a load of 50g on the other side of C at a point where the rod is again balanced.
(Students’ response: The rod is balanced)
·         Ask a student to measure the distances of 100g weight and 50g weight from the centre C (for example 20cm and 40cm respectively)
·         Explain to the students that 100g is load (L) 50g is the effort (E) and point C is the fulcrum (F). distance between effort and C is effort arm.
·         Now ask, what does it show?
(Students’ response:  if the effort arm is greater than the load arm, a lesser force can lift a heavier load. In this way a lever makes the work easier)
·         Ask students to find the examples of this kind of lever from their daily life.
(Students’ response:  Seesaw, pair of scissors and hand pump. Etc.)
·         Draw the diagrams of seesaw, scissor and hand pump on the board and ask: what is the position of fulcrum in these levers?
(Students’ response: The fulcrum is between load and effort)
##### Activity 4
·         Repeat the above activity by changing the position of the fulcrum, effort and load as shown in figure.
·         Ask students to find examples of this kind of lever from their daily life.
((Students’ response:  Door, wheel barrow and nutcracker and bottle opener etc)
·         Draw the diagrams of door, wheel barrow and nutcracker on the board and ask: What is the position of load in these levers?
(Students’ response: The load is between fulcrum and effort)

#### Activity 5

·         Repeat the above activity by changing the position of the fulcrum, effort and load as shown in figure.
·         Ask students to find the examples of this kind of lever from their daily life. ( A pair of tongs, forceps and knife etc)
·         Draw the diagrams of a pair of tongs and a knife on the board and ask:  What is the position of fulcrum, load and effort in these levers?
(The effort is between load and fulcrum)
##### Sum up/ Conclusion
Ask the students what have they learnt today and write the correct answers on the board.
·         An inclined plane is a slope or a ramp along which a load can be lifted up easily.
·         Gate entrance ramp, car ramps and parking ramp etc are some examples of inclined planes
·         Knife is also a simple machine called wedge.
·         Some examples of wedges are knife, axe, nail, pin, wedge, sledge hammer and knitting needles etc.
·         Levers are used to lift heavy weight with less effort around a pivot (fulcrum)
·         The lever can be classified into the first kind of lever, the second kind of lever and the third kind of lever based on the relative positions of the fulcrum, the effort and the load.
·         In the first kind of lever the fulcrum is between the effort and the load. E.g. a pair of scissors, pliers, a lid opener and claw hammer etc.
·         In the second kind of lever the load is between the fulcrum and effort e.g. nut cracker, bottle opener, wheel barrow and paper cutter etc.
·         In the third kind of lever the effort is between the fulcrum and load e. g. a pair of tongs, a stapler broom and arm etc.
##### Assessment
·         Make the following table on the board and ask the students to copy it on their notebooks.
·         Ask them to fill the table by giving common examples based on their knowledge and learning about lever.
·         Then ask the following assessment questions from the students
1.       How does an inclined plane make our work easier?
2.       What is the first kind of lever?
3.       What is the second kind of lever?
4.       What is the third kind of lever?
5.       How does a lever make our work easier?
·         Involve the students in solving the questions given at the end of chapter / unit in textbook.
 First kind of lever Second kind of lever Third
·         Give an example of inclined plane, wedge and each kind of lever from your daily life other than those discussed in the class and draw the diagram of each?

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