Conservation of Energy: Solving for Initial and Final Energy

In summary, the conversation discusses the state of m3 at the instant m5 hits the ground and how to use energy conservation to determine its final height. It is determined that m3 starts with a height of 4m and an upward velocity of 4.43m/s, and will reach a maximum height above 4m before coming to rest. Using energy conservation, it is calculated that the new height will be approximately 5.001m.
  • #1
Neon32
68
1

Homework Statement



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2. Homework Equations [/B]

Inital energy=Final energy
K.Ei+P.Ei=K.Ef+P.Ef

The Attempt at a Solution



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  • #2
Describe the state of m3 (position, velocity) at the instant m5 hits the floor. What do you expect to happen to m3 after that instant?
 
  • #3
gneill said:
Describe the state of m3 (position, velocity) at the instant m5 hits the floor. What do you expect to happen to m3 after that instant?
The position of m3 when m5 hits the ground is 4 m high above the ground and m3 will come to rest after that.
 
  • #4
Neon32 said:
The position of m3 when m5 hits the ground is 4 m high above the ground and m3 will come to rest after that.
It's the "m3 will come to rest after that" part that you need to look into. How fast and what direction is m3 moving at that instant? Can you think of a way to use energy conservation to find out how high m3 will go?
 
  • #5
gneill said:
It's the "m3 will come to rest after that" part that you need to look into. How fast and what direction is m3 moving at that instant? Can you think of a way to use energy conservation to find out how high m3 will go?
m3 is moving up and with velocity 4.43m/s at the instant m5 hits the ground
 
  • #6
Neon32 said:
m3 is moving up and with velocity 4.43m/s at the instant m5 hits the ground
So it starts this phase of its journey at a height of 4m and moving upward with velocity 4.43 m/s. Thus it has some initial PE and KE. What happens to the PE and KE from there?
 
  • #7
gneill said:
So it starts this phase of its journey at a height of 4m and moving upward with velocity 4.43 m/s. Thus it has some initial PE and KE. What happens to the PE and KE from there?
So you mean in the second case, the m3 will start from height 4m and velocity 4.43m and go some distance above 4m?

This is how I understood it:
Inititaly the m3 is at height 4m and inital velocity 4.43m.
so Initial energy= m3gh+1/2 m V2 (1)

Then it will move some distance above 4m until it reaches its maximum distance and comes to rest.
so Final energy of the whole system(both bodies)=m3gh(new highet)+ 0 (2)

So from (1) and (2)
m3gh+1/2 m V2=m3gh(new height)
 
  • #8
That looks good. What do you find for the new height?
 
  • #9
gneill said:
That looks good. What do you find for the new height?
height approximatley equal 5.001 m.
 
  • #10
Neon32 said:
height approximatley equal 5.001 m.
Remember to round to the correct number of significant figures. But otherwise, that looks great!
 
  • Like
Likes Neon32
  • #11
gneill said:
Remember to round to the correct number of significant figures. But otherwise, that looks great!
Thanks for taking the time to help me. Appreciated :).
 

1. What is conservation of energy?

The law of conservation of energy states that energy cannot be created or destroyed, but can only be transferred or transformed from one form to another. This means that the total amount of energy in a closed system remains constant.

2. Why is conservation of energy important?

Conservation of energy is important because it is a fundamental law of physics that helps us understand and predict the behavior of energy in various systems. It also allows us to make more efficient use of energy resources and minimize waste.

3. How is conservation of energy applied in everyday life?

Conservation of energy is applied in everyday life in many ways, such as turning off lights and appliances when not in use, using public transportation or carpooling to reduce fuel consumption, and using renewable energy sources like solar or wind power.

4. Can energy be completely conserved?

In theory, yes, energy can be completely conserved in a closed system. However, in reality, there is always some amount of energy lost to heat or other forms of energy that are not easily usable. This is known as energy dissipation.

5. How does conservation of energy relate to climate change?

Conservation of energy is closely related to climate change because the burning of fossil fuels, which release large amounts of carbon dioxide and other greenhouse gases, is a major contributor to the increasing levels of energy in the Earth's atmosphere. By conserving energy and using renewable sources, we can reduce our carbon footprint and help mitigate the effects of climate change.

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