Work Energy Method for Linear Motion

In summary, the conversation is about understanding the concept of reference datum and using it to find the height of a block. The person asking the question has already defined their datum and is asking if the red line in their diagram is the correct height. The other person then provides an equation to calculate the height using the conservation of energy. They also suggest shifting the datum to make the calculation easier.
  • #1
freshbox
290
0

Homework Statement


From my textbook there is a note that says " A reference datum must always be define in order to obtain the height h. I don't quite understand what is it trying to tell me.

I already had define my datum 1 as position 1 and datum 2 as position 2.
On my 2nd diagram , I made a red line, is that the Height that I need to find?

The Attempt at a Solution


Working for Block position 2
E2=K2+G2+S2
=1/2(10)v^2 + 10(9.81)(-h) + 0



Thanks.
 

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  • #2
I gave a try to your problem and got the answer to be 2.74 which is almost near to 2.94, that might be because i used g=10m/s^2 for simplified calculation.

The spring is compressed and released, the spring potential energy converts to kinetic energy, gravitational potential energy and some gets used up in doing work again friction. Can you make the equation now?
 
  • #3
Ignore the 1st diagram.
 

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  • #4
Hi Pranav, you are asking me to make an equation for datum 1 or datum 2?
 
  • #5
Sorry Pranav, it's getting late here, talk to you tomorrow.
 
  • #6
freshbox said:
Ignore the 1st diagram.

Ah that makes more sense, i was confused what you meant by "datum".

I am asking you to use the conservation of energy at datum 1 and datum 2. Also shift datum 1 a little back because the spring is compressed by 80mm, it will make things easier for you.
Define zero gravitational potential energy at datum 1, now what is the spring potential energy?
 

1. What is the work-energy method for linear motion?

The work-energy method for linear motion is a principle in physics that relates the work done on an object to its change in kinetic energy. It states that the net work done on an object is equal to its change in kinetic energy.

2. How is the work-energy method used in real-life applications?

The work-energy method has many practical applications in engineering and everyday life. It is used to calculate the work done by machines and to design efficient systems that conserve energy. It is also used in sports to analyze the motion and energy of athletes.

3. What is the equation for the work-energy method in linear motion?

The equation for the work-energy method is W = ΔKE = ½mv2f - ½mv2i, where W is the net work done, ΔKE is the change in kinetic energy, m is the mass of the object, and vf and vi are the final and initial velocities, respectively.

4. How does the work-energy method relate to the law of conservation of energy?

The work-energy method is based on the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred or transformed. In the work-energy method, the work done on an object is equal to its change in kinetic energy, which is a manifestation of the conservation of energy principle.

5. Can the work-energy method be used for non-linear motion?

Yes, the work-energy method can be applied to non-linear motion as long as the forces acting on the object are known and the motion is along a defined path. In these cases, the work done is still equal to the change in kinetic energy, but the equations may be more complex.

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