What is a Simple Machine?
An assembly or a particular unit of several mechanisms that are used to modify motion and the extent of a force in order to perform work is known as a simple machine. These simplest mechanisms can use power to increase force. Some of the simple machines that we see in our daily lives are the inclined plane, spring, pulleys, wheels, axle, wedge, and screw.
Read More: Concept of Simple Machines
The inclined plane
A sloping surface that is used for raising heavy bodies is known as an inclined plane. As compared to raising the weight upwards, the force required to move an object up the incline is less. This is the mechanical advantage that an inclined plane provides.
The lever
A lever is a bar mechanism that rests on a fulcrum; a fulcrum is basically a support to the lever. When we exert a downward force on one end of the lever, then it transfers the force in the upward direction at the other end, which eventually increases, due to which a heavyweight is lifted using a small force.
The wedge
A wedge is an object usually made of metal or wood that tapers to a thin edge. A force is generated in a sideways direction when the wedge is pushed in one direction. It is used in securing a hammerhead onto its handle, and other uses are splitting, lifting, or tightening.
The wheel and axle
A circular frame that revolves on a shaft or rod is known as a wheel. The wheel mechanism has always been used for raising water buckets from wells.
Important Questions on Simple Machines
1) What type of mechanism is attained if the shortest link is fixed?
a) Rocker crank mechanism
b) Double rocker mechanism
c) Double crank mechanism
d) None of these
Correct Option: (b)
Explanation: The links adjacent to the shortest link rotate continuously when it is fixed and can be defined as proper cranks. Therefore, this mechanism is named the double crank mechanism.
2) What is a Pulley?
A wheel that carries a flexible rope, cord, cable, belt or chain; its rim is known as a pulley. Pulleys are used to transmit energy and motion; they can be used singly or in combination. Pulleys are generally used in sets considered to decrease the amount of force needed to lift a heavy load.
3) What Is a Compound Machine?
When two or more simple machines are assembled together, and work simultaneously, then such a mechanism is called a compound machine. A pair of scissors is a good example of a compound machine. Two wedges and two levers are used to make a pair of scissors. A lot of time and effort is saved using a compound machine.
4) Which among the following apparatus is almost a straight-line motion machinery?
a) Russell’s machinery
b) Scott’s machinery
c) Watt’s machinery
d) None of these
Correct Option: (c)
Explanation: Watt’s machinery contains three links; one is shorter, and two of them are of equal length. The centre of the shorter link dashes an approximate straight line due to the rotation motion of the longer links. Hence, among the following mechanisms, Watt’s mechanism is almost an apparatus of a straight line, although the rest are precisely straight-line mechanisms.
5) Name the device that is used to guide the piston rod in a cylinder to have an approximate straight-line motion, used in early steam engines.
a) Peaucellier’s
b) Grasshopper
c) Chebyshev’s
d) Watt’s
Correct Option: (d)
Explanation: The mechanism used by Watt in steam engines to direct the piston into a cylinder to have motion in a straight line is known as a four-bar chain apparatus which is also known as Watt’s mechanism.
6) Which among the following is not a type of clutch?
a) Cylindrical clutch
b) Centrifugal clutch
c) Single disc clutch
d) Conical clutch
Correct Option: (a)
Explanation: When the shafts and machines are started and stopped frequently, clutches are employed in them for power transmission. Single disc, conical and centrifugal are different types of clutches. Clutches are also used in machines that are partially or fully loaded to deliver power in them.
7) The smaller driving gear of a pair of mated gears is known as _____.
a) Rack
b) Module
c) Pulley
d) Pinion
Correct Option: (d)
Explanation: The smaller driving gear of a pair of mated gears is known as pinion. It is generally used in gear train drives. The pinion helps in the turning of the wheels of the vehicle by engaging the larger gear or rack.
8) From a point on one tooth to the same point on the adjacent tooth, the distance measured along the circumference of the pitch circle is known as_____
a) Circular pitch
b) Pitch perimeter
c) Pitch radius
d) Pitch centre
Correct Option: (a)
Explanation: From a point on one tooth to the same point on the adjacent tooth, the distance measured along the circumference of the pitch circle is known as circular pitch. So basically, the circular pitch is the distance between equivalent points of consecutive gear teeth.
9) To maintain a constant angular velocity ratio between two gear tooth profiles, the condition which must be satisfied by them is called _____.
a) Law of gearing
b) Arc of contact
c) Interference
d) Contact path
Correct Option: (a)
Explanation: To maintain a constant angular velocity ratio between two gear tooth profiles, the condition which must be satisfied by them is known as the law of gearing.
10) Shoes and spiders inside the rim of the pulley are included in which of the following clutches?
a) Multi plate clutch
b) Plate clutch
c) Cone clutch
d) Centrifugal clutch
Correct Option: (d)
Explanation: Motor pulleys that contain a number of shoes inside of the rim of the pulley are combined with centrifugal clutches. Friction materials are used to cover the outer surfaces of the shoe.
Practice Questions
1) What is a simple machine?
2) What is the pulley mechanism?
3) What is the compound mechanism?
4) Define force.
5) Define 1 newton.
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