Simple Machine
SIMPLE MACHINE
a) Simple Machine:
Simple machine is a device that makes our work easier, faster and comfortable.
b) Mechanical Advantage:
The ratio of load to the effort applied on a machine is called mechanical advantage.
c) Velocity ratio:
The ratio of the distance travelled by effort to the distance travelled by load is called velocity ration.
c) Velocity ratio:
The ratio of the distance travelled by effort to the distance travelled by load is called velocity ration.
d) Efficiency:
The percentage ratio of the output work to the input work is called efficiency of a machine.
2) Write the formula of Mechanical advantage and velocity ratio.
3) What is lever? The efficiency of lever is always less than 100%, why?
Ans: A lever is a simple machine which consists of a rigid bar which is free to turn about a fixed point called fulcrum.
The efficiency of a lever is always less than 100% because some energy (input work) is always wasted to overcome friction and move parts of the machine.
4) What is perfect or ideal machine? Write two examples of second class lever.
Ans: The machine which has 100% efficiency is called an ideal machine or perfect machine.
5) What do you mean by the efficiency of a simple machine is 80%?
Ans: A machine has efficiency 80%, it implies that 80% of the input work is obtained as output work and remaining 20% of the energy supplied is lost in machine to overcome friction.
6) What is output and input work?
Output work: The work done by the machine is called output work.
OR
The product of load and distance through which load is moved is called output work.
Input work: The work done on a machine is called input work.
OR
The product of force and distance through which force is applied is called input work.
7) What is second class lever? Write an example of it.
Ans The lever in which load lies in between fulcrum and effort is called second class lever. E.g. nut cracker, wheel barrow, bottle opener, mango cutter, etc.
8) Write down the principle of lever.
Ans: In friction less condition, load x load arm = effort x effort arm.
When a lever is in equilibrium condition, the product of load and load arm is equal to product of effort and effort arm.
9) In which class of lever, shovel and physical balance lie?
Ans: Shovel = Third Class Lever
Physical Balance = First Class Lever
10) Write any two functions of simple machine.
Ans: The following are the two functions of simple machine;
i. To multiply the force applied
ii. To change the direction of applied force.
11) Why is the MA always less than VR?
Ans: MA is always less than VR because Mechanical Advantage decreases due to the friction and weight of moving parts of the machines where as the velocity ratio remains constant.
12) How does simple machine makes our work easier? Write two examples of third class lever.
Ans: Simple machine makes our work in the following ways;
i) By multiplying force
ii) It helps to change the direction of applied force.
iii) By transferring force from one point to another point.
Shovel and Fishing rod are the two examples of Third class lever.
13) What is the principle of simple machine?
Ans: If there is no loss of energy due to any cause, in such a case
Input work = output work
This is called principle of simple machine.
14) Why MA has no unit?
Ans: MA has no unit because it is a ratio of two similar quantities.
15) What is the principle of Lever?
Ans: In friction less condition;
Load X Load Arm = Effort X Effort Arm
This is the principle of lever.
16) Long spanner is required to open a tight bolt, why?
Ans: Long spanner is required to open a tight bolt because if handle is long, effort arm increases which increases the mechanical advantages that makes easy to open by magnifying force.
Label: science8, simple machine, lever, types of lever, principle of lever, why MA has no unit?, why MA is always less than VR, basiclevelschool,
Ans: A lever is a simple machine which consists of a rigid bar which is free to turn about a fixed point called fulcrum.
The efficiency of a lever is always less than 100% because some energy (input work) is always wasted to overcome friction and move parts of the machine.
4) What is perfect or ideal machine? Write two examples of second class lever.
Ans: The machine which has 100% efficiency is called an ideal machine or perfect machine.
5) What do you mean by the efficiency of a simple machine is 80%?
Ans: A machine has efficiency 80%, it implies that 80% of the input work is obtained as output work and remaining 20% of the energy supplied is lost in machine to overcome friction.
6) What is output and input work?
Output work: The work done by the machine is called output work.
OR
The product of load and distance through which load is moved is called output work.
Input work: The work done on a machine is called input work.
OR
The product of force and distance through which force is applied is called input work.
7) What is second class lever? Write an example of it.
Ans The lever in which load lies in between fulcrum and effort is called second class lever. E.g. nut cracker, wheel barrow, bottle opener, mango cutter, etc.
8) Write down the principle of lever.
Ans: In friction less condition, load x load arm = effort x effort arm.
When a lever is in equilibrium condition, the product of load and load arm is equal to product of effort and effort arm.
9) In which class of lever, shovel and physical balance lie?
Ans: Shovel = Third Class Lever
Physical Balance = First Class Lever
10) Write any two functions of simple machine.
Ans: The following are the two functions of simple machine;
i. To multiply the force applied
ii. To change the direction of applied force.
11) Why is the MA always less than VR?
Ans: MA is always less than VR because Mechanical Advantage decreases due to the friction and weight of moving parts of the machines where as the velocity ratio remains constant.
12) How does simple machine makes our work easier? Write two examples of third class lever.
Ans: Simple machine makes our work in the following ways;
i) By multiplying force
ii) It helps to change the direction of applied force.
iii) By transferring force from one point to another point.
Shovel and Fishing rod are the two examples of Third class lever.
13) What is the principle of simple machine?
Ans: If there is no loss of energy due to any cause, in such a case
Input work = output work
This is called principle of simple machine.
14) Why MA has no unit?
Ans: MA has no unit because it is a ratio of two similar quantities.
15) What is the principle of Lever?
Ans: In friction less condition;
Load X Load Arm = Effort X Effort Arm
This is the principle of lever.
16) Long spanner is required to open a tight bolt, why?
Ans: Long spanner is required to open a tight bolt because if handle is long, effort arm increases which increases the mechanical advantages that makes easy to open by magnifying force.
Label: science8, simple machine, lever, types of lever, principle of lever, why MA has no unit?, why MA is always less than VR, basiclevelschool,