Does this require More energy?

  • Context: Undergrad 
  • Thread starter Thread starter pallidin
  • Start date Start date
  • Tags Tags
    Energy
Click For Summary

Discussion Overview

The discussion revolves around the question of whether raising a bowling ball that is in motion requires more upward force compared to raising a stationary bowling ball. The context includes experimental conditions involving horizontal movement and vertical force application, exploring concepts of momentum and force in physics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant assumes that raising a moving bowling ball requires more upward force than raising a stationary one, based on the idea that horizontal momentum influences vertical thrust.
  • Another participant questions the assumption, asking why the force required would depend on the horizontal speed of the ball.
  • A participant expresses skepticism about the relationship between horizontal velocity and the force needed for vertical acceleration, suggesting that a planar vector shift would not affect energy expenditure differently for static versus moving masses.
  • One participant argues that the same vertical force exerted through the same vertical displacement performs the same amount of work, indicating that horizontal displacement is irrelevant to the force required to support the weight of the bowling ball.
  • Another participant points out that the question is ill-defined, noting that more force could be applied in the second case, but the energy involved remains the same.
  • A participant acknowledges the complexity of the topic and expresses gratitude for the insights provided by others.
  • A final comment states that perpendicular vectors are independent of each other, suggesting a perspective on the relationship between horizontal and vertical forces.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between horizontal motion and the force required for vertical movement. There is no consensus on whether horizontal momentum affects the upward force needed, and the discussion remains unresolved regarding the implications of these concepts.

Contextual Notes

The discussion includes assumptions about the influence of horizontal motion on vertical force, which may depend on definitions and interpretations of momentum and force. The lack of clarity in the initial question also contributes to the complexity of the discussion.

pallidin
Messages
2,207
Reaction score
3
Question scenario:

Let's say that we have a heavy bowling ball and roll it across a horizontal platform that can be vertically raised.

Experimental condition #1: The bowling ball is not moving, and I raise the platform with X amount of force directly underneath the static ball to raise the ball 1-foot.

Experimental condition #2: the bowling ball is given a forceful horizontal movement along the surface of the horizontal platform and, at mid-point of travel, I raise the platform directly underneath the ball to raise the ball 1-foot.

Does condition #2 require more upward force than #1 ?

This is not a homework Q. Just curious. I assume the answer is yes.
 
Physics news on Phys.org
Why would you assume yes? Why would the amount of force required to raise the platform depend on the horizontal speed of the ball?
 
Doc Al said:
Why would you assume yes? Why would the amount of force required to raise the platform depend on the horizontal speed of the ball?

I don't know, Doc, that's why I'm asking.

Doc, my assumption, perhaps erroneous, is based on my notion that a horizontal momentum influences a vertical thrust.
I find it rather odd that horizontal momentum does not negatively influence an outside vertical.
Granted, the vectors are not opposing, but surely there would be a resultant vector shift. Perhaps this resultant vector shift does not oppose the applied vertical force, so, I have another question:

Does your answer also apply with respect to a accelerating ball?
 
I fail to see why a horizontal velocity (or acceleration) would have any bearing on the force required to produce a vertical acceleration.
 
Doc Al said:
I fail to see why a horizontal velocity (or acceleration) would have any bearing on the force required to produce a vertical acceleration.

I find it hard to believe that a planar vector shift expends the same energy on a static-vs-moving mass. But I'm sure you are correct.

Post edited.
 
Last edited:
Not sure what you mean by "planar vector shift". The same vertical force exerted through the same vertical displacement will perform the same amount of work. (The horizontal displacement is irrelevant.)

To just support the bowling ball a normal force is required. Does a horizontally moving ball require a greater normal force to support its weight? No.
 
The question is ill-defined. You could apply more force case 2 if you wanted to - you haven't said how fast you are accelerating the bowling ball upwards in either case.

The energy (from your title) is the same though: gmh.
 
Very good. Thanks to both Doc and Russ for helping me to understand this better. I have always loved physics, and even know a thing or two, but sometimes the basics stump me!
 
perpendicular vectors are independent of each other
 

Similar threads

Undergrad Question about an interesting experiment video (two magnetic balls in tubes)
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Seemingly a contradiction of conservation of energy?
  • · Replies 51 ·
2
Replies
51
Views
5K
Undergrad Is Mechanical Energy Conservation Free of Ambiguity - follow up
  • · Replies 77 ·
3
Replies
77
Views
7K
High School How to shoot longer shots in basketball
  • · Replies 20 ·
Replies
20
Views
3K
Undergrad Acceleration on an electric unicycle, how much does the rider have to lean?
  • · Replies 30 ·
2
Replies
30
Views
4K
Undergrad Is it possible to "violate" momentum at the expense of more energy?
  • · Replies 2 ·
Replies
2
Views
1K
High School Why is my experimental spring constant an order of magnitude off?
  • · Replies 4 ·
Replies
4
Views
2K
High School The physics of flywheel launchers (like tennis ball shooters)
  • · Replies 60 ·
3
Replies
60
Views
8K
Undergrad How weather conditions affect a golf shot
  • · Replies 6 ·
Replies
6
Views
4K
High School How Does Energy Transfer Work in Pendulums?
  • · Replies 3 ·
Replies
3
Views
2K