Energy conservation question help?

In summary: Once it reaches point B, all its energy is potential energy and it will not roll any higher. It will stop at point B. So it cannot reach point C.
  • #1
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The sphere with the mass 1 kg is released from point A without initial speed and moves without friction just like in the figure.
a) Find the mechanic energy in point A
Solution : E=mgh because v=0
b) Find the kinetic energy in B
Using the law of the conservation of mechanic energy, mghA=mghB+Ekb
C) WILL THE SPHERE REACH THE POINT C?

To reach the C point, Emb=Emc
so mghB+ Ekb=mghC+ Ekc
here i find the V of C.BY proving that the ball has a speed in C ,do I prove it reaches the point?

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  • #2


Elaia06 said:
a) Find the mechanic energy in point A
Solution : E=mgh because v=0
b) Find the kinetic energy in B
Using the law of the conservation of mechanic energy, mghA=mghB+Ekb
OK.
C) WILL THE SPHERE REACH THE POINT C?

To reach the C point, Emb=Emc
so mghB+ Ekb=mghC+ Ekc
here i find the V of C.BY proving that the ball has a speed in C ,do I prove it reaches the point?
Try it and see. Even easier is to compare the energy at A with the energy at C.
 
  • #3


is it correct the c question?
 
  • #4


Elaia06 said:
is it correct the c question?
The basic approach is correct. Compare the energy at A with the energy at C. What would the velocity of the sphere be at that point? Is it possible?
 
  • #5


The energy at A is 25 J.The energy at C is 35.Velocity at a is zero.Velocity at C is sqrt10.Seems possible.
 
  • #6


Elaia06 said:
The energy at A is 25 J.The energy at C is 35.
Better check those numbers, especially the second. I presume you mean that to be the gravitational PE at C.
Velocity at a is zero.Velocity at C is sqrt10.Seems possible.
Really? Even though you found that just the PE alone is greater at C than the entire energy at A? How did you solve for the velocity at C. Show the equation.
 
  • #7


The law of the conservation of the mechanical energy For points B and C

mghB+ Ekb=mghC+ Ekc
1*10*1.5+10=1*10*3+1*V^2/2
so here V=sqrt10
what does the energy at A have to do with the energy at C? I mean, I found that it has a speed at C,isnt that enough?
 
  • #8


Elaia06 said:
The law of the conservation of the mechanical energy For points B and C

mghB+ Ekb=mghC+ Ekc
1*10*1.5+10=1*10*3+1*V^2/2
Let's do the math:
15 + 10 = 30 + KE
25 = 30 + KE
so... KE = -5 Oops! Can KE be negative?
so here V=sqrt10
what does the energy at A have to do with the energy at C?
Energy is conserved, so it's the same at A, B, and C.
 
  • #9


Sorry, u are right :) So there is no kinetic energy at point C,which means that there is no velocity,so the ball can't reach that point.right now?
What if the velocity would be let's say 5 m/s,would the ball reach the C then?
 
Last edited:
  • #10


Right. The sphere cannot roll to a point higher than where it started.
 

What is energy conservation?

Energy conservation refers to the practice of reducing energy consumption in order to preserve natural resources and protect the environment. This can be achieved through various methods such as using energy-efficient technologies and adopting sustainable practices.

Why is energy conservation important?

Energy conservation is important because it helps to reduce our dependence on non-renewable energy sources, which are finite and contribute to pollution and climate change. It also helps to save money on energy bills and promote a more sustainable future.

How can I conserve energy at home?

There are several ways to conserve energy at home, such as turning off lights and electronics when not in use, using energy-efficient appliances, insulating your home to reduce heating and cooling needs, and using natural lighting whenever possible.

What are some benefits of energy conservation?

Some benefits of energy conservation include reducing greenhouse gas emissions, preserving natural resources, saving money on energy bills, and promoting a more sustainable future for generations to come.

What role can individuals play in energy conservation?

Individuals can play a significant role in energy conservation by adopting energy-efficient practices in their daily lives, such as using public transportation, carpooling, and turning off lights and electronics when not in use. By making small changes, individuals can collectively make a big impact on energy conservation efforts.

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