Advertisements
Advertisements
प्रश्न
If the energy of a ball falling from a height of 10 metres is reduced by 40%, how high will it rebound?
Advertisements
उत्तर
Given:
Height (h1) = 10 m
PE2 = PE1 - PE1 of 40%
Find: Height (h2)
Formula: P.E. = mgh
Calculations:
PE1 = mgh1 ...(i)
PE2 = mgh2 ...(ii)
PE2 = PE1 of 60%
Dividing equation (ii) by (i).
`"PE"_2/"PE"_1 = ("mgh"_2)/("mgh"_1)`
`(60%"PE"_1)/("PE"_1) = "h"_2/10`
`60/100 = "h"_2/10`
`"h"_2 = (60 xx 10)/100`
h2 = 6 m
∴ The ball will bounce up to a height of 6 m when it hits the ground.
APPEARS IN
संबंधित प्रश्न
Write true or false of the following statement.
Potential energy changes into kinetic energy when it is put to use
Fill in the blank
An electric fan converts electrical energy into ______ energy.
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 |
Select the correct alternatives
When we rub our hands
What is potential energy ? State its unit.
What do you mean by conservation of mechanical energy? State the condition when does it hold.
Define the term efficiency of a machine.
Tick the most appropriate answer.
The force applied on a machine to do work is called the
How many joules are there in one kilowatt-hour?
What is the common name of '1 kWh' of electrical energy?
The commercial unit of energy is :
Observe the picture and put a tick (✓) if work is done and put a cross (x) if work is not done.
 |
 |
 |
 |
 |
 |
Running water possesses ______.
Find out the form of energy possessed by the following thing.
A rock on the top of a hill
What energy transfer happen in a car engine?
When a body falls freely towards the earth, then its total energy
Which one of the following is not the unit of energy?
Define kilowatt hour.
