Principle of Conversation Of Energy question

In summary, two objects, a 5kg and a 3kg, are connected by a light string passing over a light frictionless pulley. The 5kg object is released from rest and falls 4m before hitting the ground. Using the principle of conservation of energy, the speed of the 3kg object can be determined just as the 5kg object hits the ground. The equation for this is 2.5v^2= 78.4, resulting in a velocity of 5.6m/s for the 3kg object. Additionally, the acceleration of the 5kg object can be calculated by drawing a free body diagram and using the conservation of energy equation for the 3kg mass.
  • #1
alexyvettea
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Homework Statement



2 objects are connected by a light string passing over a light frictionless pulley. The 5kg object is released from rest. Using the principle of conservation of energy, (a) determine the speed of the 3kg object just as the 5kg object hits the ground


The picture shows the 3kg object at rest connected by a string to a pulley vertically...and the 5kg object hangin from a string from the pulley with 4m height between the ground and the 5kg object.




Homework Equations



4.43m/s is answer to a



The Attempt at a Solution



.5mv^2 + g(mf-mi)y=.5(5)v^2 + (-9.8)(2)(4)===>

2.5v^2= 78.4
v=5.6m/s
 
Last edited:
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  • #2
When the 5kg object is released from rest, its acceleration in not g. Calculate its acceleration by drawing free body diagram. 3 kg moves up with the same acceleration. Then apply the conservation of energy for 3 kg mass to calculate its velocity.
 
  • #3
Draw An F.b.d.
 

What is the Principle of Conversation of Energy?

The Principle of Conversation of Energy is a fundamental concept in physics that states that energy cannot be created or destroyed, but can only be transformed from one form to another. This means that the total amount of energy in a closed system remains constant over time.

How is the Principle of Conversation of Energy applied in everyday life?

The Principle of Conversation of Energy can be seen in various phenomena in our daily lives. For example, when we turn on a light bulb, electrical energy is converted into light and heat energy. When we burn wood in a fire, chemical energy is converted into heat and light energy. This principle also explains why perpetual motion machines are impossible, as they would violate the conservation of energy.

What are the different forms of energy according to the Principle of Conversation of Energy?

According to this principle, energy can exist in various forms such as mechanical, thermal, electrical, chemical, nuclear, and electromagnetic. These forms of energy can be converted from one to another, but the total energy in the system remains the same.

How is the Principle of Conversation of Energy related to the laws of thermodynamics?

The Principle of Conversation of Energy is closely related to the first law of thermodynamics, which states that energy cannot be created or destroyed, but can only be transferred or converted from one form to another. This principle also forms the basis for the second law of thermodynamics, which states that in any energy transformation, some energy will be lost as heat.

What happens when the Principle of Conversation of Energy is violated?

If the Principle of Conversation of Energy is violated, it would mean that energy is being created or destroyed, which goes against the fundamental laws of physics. This can lead to unpredictable and potentially catastrophic consequences, as it would mean that the laws of nature are not consistent or reliable.

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