Do A and C have same or different KE at the end?

In summary, the conversation discusses the conservation of energy in a frictionless ramp scenario. The question is whether two blocks, A and C, should have the same final kinetic energy despite traveling different horizontal distances. The answer is yes, as the conservation of energy dictates that the final kinetic energy should be equal to the initial potential energy. The answer template provided is a bit misleading but ultimately, the ranking of A and C in terms of their final kinetic energy does not matter.
  • #1
JessicaHelena
188
3

Homework Statement



Please look at the attached screenshot.

Homework Equations



Assuming the ramp is frictionless, Ei = Ef and thus mgh = KE ( = 1/2mv^2, which isn't really necessary here)

The Attempt at a Solution


I'm okay with all other examples except for A and C. From the answer template given, I don't think I'm allowed to let two different blocks have the same final KE, but even though C travels a shorter horizontal distance, the conservation of energy tells me they should have the same KE at the end (bc their mgh is the same)! Am I missing something here?
 

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  • #2
You are correct and the answer template is a bit misleading. Conclusion: A and C can be entered in the order of your choice. Or in one box if the work is judged by a human instead of a counting machine.
 
  • #3
JessicaHelena said:
I'm okay with all other examples except for A and C. From the answer template given, I don't think I'm allowed to let two different blocks have the same final KE, but even though C travels a shorter horizontal distance, the conservation of energy tells me they should have the same KE at the end (bc their mgh is the same)! Am I missing something here?

I don't think so - since there are no losses - the final KE should be same as initial PE - mgh as you indicated. I guess in the template it wouldn't matter if you rank AC or CA in either order.
 
  • #4
Alright, I'll put it that way then. Thank you!
 

1. Is kinetic energy (KE) the same thing as potential energy (PE)?

No, kinetic energy (KE) and potential energy (PE) are two different types of energy. Kinetic energy is the energy an object possesses due to its motion, while potential energy is the energy an object has due to its position or composition.

2. How is kinetic energy (KE) calculated?

Kinetic energy (KE) is calculated using the formula KE = 1/2 * m * v^2, where m is the mass of the object and v is the velocity (speed) of the object.

3. Can two objects with the same mass have different kinetic energies?

Yes, two objects with the same mass can have different kinetic energies if they have different velocities. An object with a higher velocity will have a greater kinetic energy than an object with a lower velocity.

4. How does temperature affect the kinetic energy of a substance?

Temperature is a measure of the average kinetic energy of the particles in a substance. As temperature increases, the particles move faster and therefore have higher kinetic energies.

5. Can kinetic energy be negative?

No, kinetic energy cannot be negative. It is always a positive value, as it represents the energy of an object in motion. However, the direction of the motion can be negative if the object is moving in the opposite direction of the chosen reference point.

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