CHAPTER - SIMPLE MACHINES
Long-answer questions.
a. Briefly describe how an inclined plane, a wedge and a pulley make our work easier.
b. Write in short about the three classes of lever with examples.
c. What do you mean by fulcrum, load and effort in a lever? Draw a simple diagram.
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Answers
Answer:
ans a
inclined plane- Using an inclined plane makes it easier to move an object. It takes less force to move an object in an upward direction on an inclined plane than it does to lift the object straight up. ... However, the inclined plane reduces the force needed to do the work.
wedge- wedge is a simple machine that consists of two inclined planes, giving it a thin end and thick end. ... A wedge makes work easier by increasing the force applied to the object, although it applies the force over a shorter distance. This gives the wedge a mechanical advantage greater than 1.
answer b
There are three classes levers, according to the position of the fulcrum. Class 1 has the fulcrum placed between the effort and load. Class 2 has the load between the effort and the fulcrum. Class 3 has the effort between the load and the fulcrum.
Examples include see-saws, crow bars, hammer claws, scissors, pliers, and boat oars. The claw end of a hammer, along with the handle, is a Class 1 Lever.
wheelbarrow, a bottle opener, and an oar are examples of second class levers.
third class levers the effort is between the load and the fulcrum, for example in barbecue tongs.
answer c
lever is a simple machine made of a rigid beam and a fulcrum. The effort (input force) and load (output force) are applied to either end of the beam. The fulcrum is the point on which the beam pivots. When an effort is applied to one end of the lever, a load is applied at the other end of the lever.
Answer:
a.Inclined planes make it easier to move objects to a higher elevation. The sloping surface of the inclined plane supports part of the weight of the object as it moves up the slope. As a result, it takes less force to move the object uphill.A wedge is a simple machine that consists of two inclined planes, giving it a thin end and thick end. ... A wedge makes work easier by increasing the force applied to the object, although it applies the force over a shorter distance.Pulleys are powerful simple machines. They can change the direction of a force, which can make it much easier for us to move something. ... Pulleys can also provide us with a mechanical advantage when we use several together and more rope. This process lessens the amount of force required to lift something.
b.First Class Lever
This is a type of lever which has the fulcrum in between the weight and the force applied. Its order is represented as force-fulcrum-weight. This is the most basic type of lever.
Example:
Our hand pushing an object or seesaws, crowbars.
Using scissors represents the use of two first-class levers.
A wheel and axle is also an example.
Pulling a nail out of a wooden plank also represents a first-class lever.
Second Class Lever
In this, the fulcrum is at one end and the force applied is on the other end. The weight is situated in the middle of these two. The order of this would be fulcrum-weight-force. The application of force at one end will result in some work done on the other end.
Example:
Wheelbarrow
Staplers
Doors or gates
Bottle openers
Nutcracker
Nail clippers
Third Class Lever
These are the levers in which the fulcrum is at one end and the force is applied in the middle and the weight is on the other end. The order is represented as a weight-force-fulcrum. In this case, we have to apply more energy to displace the weight to a longer distance.
Example:
Fishing rod
A broom
A baseball bat
A bow and arrow
Human jaw
c.Fulcrum:the point against which a lever is placed to get a purchase, or on which it turns or is supported.
The object that is lifted on the other end is called the load
A force called the effort
