2021-22 EVS CH SIMPLE MACHINES (NB AND WB EX)
2021-22 EVS CH SIMPLE MACHINES (NB AND WB EX)
NEW WORDS H.W
inclined
bolt
rigid
wedge
fulcrum
NEW TERMS
bolt – a movable rod that when slid into a socket fastens a door, gate, etc.
rigid – non-flexible
Answer the following questions.
a. What are simple machines?
ANS. A simple machine is a tool that helps us move a load by applying less force. The force applied is called effort.
b. What is a screw?
ANS. A screw is a simple machine that is a modified inclined plane that winds around a cylindrical core to form a spiral.
c. Why a wheel cannot be used as a machine without an axle?
ANS. A piece of rod passing through the centre of a wheel is called an axle. The axle supports the wheel and allows the wheel to turn on the same axis. Without an axle, a wheel cannot be used as a machine.
d. Give an example in the human body where a class- one lever is found.
ANS. An example of a class one lever is the joint between the skull and the vertebral column. The vertebral column is the fulcrum. When you nod, the neck muscles at the back of the skull provide the force (effort) to lift your head up against the weight of the head (load). When the neck muscles relax, your head nods forward.
HOTS (PLEASE DO BY YOURSELF)
Some simple machines belong to more than one type, for example, a trolley can be a lever as well as a wheel and axle. Can you think of one more simple machine that belongs to more than one type?
WORKBOOK EXERCISE CLICK ON THE LINK BELOW
