Spring, Block, KE, PE, Incline Problem: Why is KE=ZERO?

AI Thread Summary
In the discussion about a block on an inclined ramp compressed against a spring, the key point is that the change in kinetic energy (KE) is zero because both the initial and final states of the block are stationary, meaning its velocity is zero at both points. This is clarified by the fact that the block starts from rest and comes to a stop after moving up the incline. The calculations show that without friction, the block moves 2.26 meters up the incline, while with a coefficient of kinetic friction of 0.400, it moves 1.84 meters. Understanding the concept of stationary states is crucial for grasping the energy considerations involved. The discussion highlights the importance of initial and final conditions in energy problems.
ladyrx2020
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Spring, Block, KE, PE, Incline Problem: Why is KE=ZERO??

A 250 g block is pressed against a spring of force constant 1500 N/m until the block compresses the spring 8.0 cm. The spring rests at the bottom of a ramp inclined at 60.0 degrees to the horizontal. Using energy considerations, determine how far up the incline the block moves from its initial position before it stops if:

a) the ramp exerts no friction force on the block

b) if the coefficient of kinetic friction is 0.400



Can someone explain to me why is the change in kinetic energy = to zero??



The solutions says KE is zero because initial and final states are stationary. What does that mean? Doesn't the box move...

Maybe I don't fully understand the concepts...

Answers:
a) 2.26 m
b) 1.84 m
 
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ladyrx2020 said:
Can someone explain to me why is the change in kinetic energy = to zero??

When you start, your velocity is zero, when you stop it's zero again.
 


mishek said:
When you start, your velocity is zero, when you stop it's zero again.

Ohhh! I see! Wow that was a quick reply to my first post ever. Hahaha thanks a bunch! x3 :!)
 

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