A body of mass 100 kg is at rest at height 100 m above the ground ,falls through a height of 60m. Calculate Total energy, P.E. and K.E. at first and second position.(class 11th, chapter work, energy and power)
CAUTION : ONLY ANSWERS
Answers
Given:-
- Mass ,m = 100kg
- Height ,h = 100m
- Height ,h' = 60m
To Find:-
- Total energy, P.E. and K.E. at first and second position.
Solution:-
Before Going to Solve this Problems let's know what Work Energy theorem states !!
The Work Energy theorem states that energy can neither be created or nor be destroyed it can be transferred from one Position to another .
Let's Solve the Solve
Case1
Energy at 1st Position
As we know that Potential Energy is the energy possed due to height. while the energy possed by body due to motion is called Kinetic Energy.
• PE = mgh
where
PE is the Potential Energy
m is the mass of body
g is the acceleration due to
h is height attained by the object
Acceleration due to gravity is 9.8m/s²
Potential Energy at 1st Position .
➨ PE = mgh
➨ PE = 100×100×9.8
➨ PE = 100×980
➨ PE = 98000J
➨PE = 98000/1000Kj = 98KJ
Therefore, Potential Energy at 1st Position is 98 KiloJoules.
Here the Potential Energy Gets Converted into Kinetic Energy . Therefore the Kinetic Energy of the body is 98 KiloJoules.
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Case2:-
When the body fall through the height 60 m . Therefore, the Position of the body is 100-60 = 40m. and the Potential Energy gets converted into Kinetic Energy.
Now, Calculating Kinetic Energy at this Stage
• KE = mgh
Substitute the value we get
➨ KE = 100×9.8×40
➨KE = 980×40
➨KE = 39200 J
➨KE = 39200/1000Kj = 39.2 KJ
Therefore, the Kinetic Energy at this stage is 39.2 KiloJoules.
The Potential Energy at this stage will be 39.2 KiloJoules.
Answer:
=> P = mgh
=> P = 100×100×9.8
=> P = 100×980
=> P = 98000J
=> P = 98000/1000Kj = 98KJ
Potential Energy = Kinetic Energy
Kinetic energy = 98kJ
And
K = mgh
=> K = 100×9.8×40
=>K = 980×40
=>K = 39200 J
=> K = 39200/1000KJ= 39.2 KJ
Kinetic Energy = Potential Energy
P = 39.2 KJ