Advertisements
Advertisements
Question
What do you mean by conservation of mechanical energy? State the condition when does it hold.
Advertisements
Solution
This means “The total MECHANICAL ENERGY (P.E + K.E) of an isolated system at any instant is equal to the sum of kinetic ENERGYand the potential ENERGY.”
Condition : Condition under which the mechanical energy is conserved is “WHEN THERE ARE NO FRICTIONAL FORCES.” In other words the mechanical energy is conserved strictly in vacuum where friction due to air is absent.
APPEARS IN
RELATED QUESTIONS
Write true or false of the following statement.
In an electric fan, electrical energy changes into the mechanical energy.
Fill in the blank
The ability to do work is called ______
Match the following columns
| COLUMN A | COLUMN B |
| 1. Running water | 1. heat energy |
| 2. Burning | 2. vibrations |
| 3.Energy | 3.atom bomb |
| 4.Sound energy | 4.kinetic energy |
| 5.Nuclear energy | 5.joule |
State two factors on which the potential energy of a body at a certain height above the ground depends.
Answer the following in short.
What do you understand by the term efficiency of a machine’?
Give a reason for the following.
The efficiency of a machine is always less than 100%.
Name the commercial unit of measurement of energy.
Name the quantity whose unit is :
(a) kilowatt
(b) kilowatt-hour
The commercial unit of energy is :
When a body falls freely towards the earth, then its total energy
