Solving these non-numerical problems applying work and energy concepts

In summary, the conversation discusses the motion of a block on a frictionless surface and the preference of seasoned hikers to step over fallen logs. The first part involves comparing the speeds of the block at points B and C, with the conclusion that the speed at C will be greater than 2vB. In the second part, the concept of work and energy is introduced, with the suggestion to use the equation of motion to determine the speed of the block at points B and C. The conversation also mentions that this topic is related to work and energy practice, and prompts the listener to compare the work done through different displacements and determine the form of energy involved. Finally, the conversation hints at the formula for kinetic energy and its relevance to
  • #1
jrd007
159
0
Here they are...

(1) A hand exerts a constant horizontial force on a block that is free to slide on a frictionless surface. The block starts from rest at point A, and by the time it has traveled a distance d to point B it is traveling with speed vB. When the block has traveled another distance d to point C, will it's speed be greater than, less than, or equal to 2vB? Explain your reasoning.

My drawling, if you can undertand it...

Hand pushes block----------------------------------------<(surface)
~~~~~~~~~~~A----d----B----d----C

My first instinct is to say equal to since it is a frictionless surface therefore nothing will slow it down.

(2) Seasoned hikers prefer to step over a fallen log in their path rather than stepping on top and jumping down on the other side. Explain.

No idea... but I was thinking because it takes twice as much energy to step on top of and then down than it does to just stepp over?

(Thanks to all who help)
 
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  • #2
Part 1)
The block is pushed with a constant force, hence a constant acceleration.
The block is accelerating from A to B and from B to C.
Can you now compare the velocities at B and C again ?

Part 2)
It takes more energy, yes. Think potential.
 
  • #3
So the velocity with be more when it reaches B-C?

I was thinking they would be equal... I guess not.
 
  • #4
Greater than, because it is gaining momentum?
 
  • #5
Have you worked out the eqn of motion for the block ?

Use this to determine the speed of the block at the points B and C.

Use these results as justification for your answer to the question posed.
 
  • #6
This was supposed to be Work & Energy practice, right?
Compare Work done thru the displacement "a" to "b"
with Work done thru displacement from "a" to "c".
What form of Energy does this Work show up as?
What's the functional form ("formula") for KE?
 

Related to Solving these non-numerical problems applying work and energy concepts

1. How do work and energy concepts apply to non-numerical problems?

Work and energy concepts can be applied to non-numerical problems by understanding that work is the transfer of energy from one form to another, and energy is the ability to do work. This means that even in non-numerical scenarios, energy is still being transferred and utilized to produce a desired outcome.

2. How can I approach solving non-numerical problems using work and energy concepts?

When solving non-numerical problems using work and energy concepts, it can be helpful to first identify the different forms of energy involved in the problem and how they are being transferred. Then, apply the laws of conservation of energy and work to determine how the system will behave and what the final outcome will be.

3. Can work and energy concepts be used to solve real-world problems?

Yes, work and energy concepts can be applied to solve real-world problems. In fact, many real-world scenarios involve the transfer and transformation of energy, making these concepts essential for understanding and solving such problems. For example, work and energy concepts are used in engineering to design machines and structures that efficiently use energy.

4. Are there any limitations to using work and energy concepts to solve non-numerical problems?

While work and energy concepts are very useful in solving non-numerical problems, they do have their limitations. These concepts are based on certain assumptions and ideal conditions, so they may not always accurately represent real-world situations. Additionally, some problems may involve a combination of work, energy, and other concepts that must be considered for a complete solution.

5. How can I improve my problem-solving skills using work and energy concepts?

To improve your problem-solving skills using work and energy concepts, it is important to practice applying these concepts to a variety of problems. Additionally, studying and understanding the mathematical equations and principles that govern work and energy can also help in solving more complex problems. Collaborating with others and seeking guidance from a teacher or mentor can also aid in improving problem-solving skills.

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