Kinetic Energy and Work Homework with Experiments and Calculations

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Homework Help Overview

The discussion revolves around a physics homework problem related to kinetic energy and work, involving experiments with a ball and springs. The original poster presents a series of calculations and questions regarding the motion and energy of the ball at various points in its trajectory.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to analyze the motion of the ball, calculate its speed, and determine the work done on it. Participants question the assumptions regarding the spring's force and the definitions of energy in the context of the problem. There are discussions about the conditions of the experiment, such as neglecting rolling and spinning, and clarifications about the energy types involved.

Discussion Status

Participants are actively engaging with the problem, raising questions about missing information and clarifying definitions. Some have provided insights into the assumptions made, while others are seeking further details about the experiment's setup. There is no explicit consensus on the interpretations, but the dialogue is productive in exploring various aspects of the problem.

Contextual Notes

There are indications that some verbal descriptions of the experiment may be missing, which could affect the understanding of the problem. Participants are also considering the implications of neglecting certain forces and the definitions of energy in the system.

harelori
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Homework Statement


*The experiments drawing is attached.
m=0.1kg
Ek at point O (the moment the ball is being pushed) = 1.25 J
D (0 ; 0) , C (0 ; 0.05), E (0.25 ; 0), F (0.50 ; 0), G (0.75 ; 0)
Friction is neglected

1.Complete the chart by typing if the value of each variable is rising / decreasing / constant / equals to zero. (attachment added)
2.Calculate the balls speed at point O.
3.Calculate the work of ∑F that has been working on the ball from A to C. ( W∑F )
4.The ball reaches one of the holes G/F/E - calculate which one it reaches.
5.Add Cartesian axis on the drawing, locate in it the points :C,D,E,F,G and add to the drawing the route of the ball from point C until the point he touches the ground.
6.Players has springs that pushes the spring with a constant F that is higher/lower than the original spring. Which one does one has to use for the ball to fall after point G? (The distance of AA' stays the same)

*I'm having difficulties with basically everything*

Homework Equations


Ek=mv^2/2
W=Fx*cosα
W∑F=ΔEk
1/2kΔx^2
W=-ΔU
U=mgh

The Attempt at a Solution



1. At point A'O: v:rising , a:rising, ∑F:constant, Mechanic Energy: rising
At point OC: v:constant , a:0, ∑F:constant, Mechanic Energy: constant.
From point C until the ball touches the ground: v:constant, a:rising, ∑F:rising, Mechanic Energy: constant.

2.
Ek=mv^2/2 => 1.25 = 0.1v^2/2 => 2.5= 0.1v^2 => v=5 m/s

*If the question has anything missing - please write the answer you would have done just without placing the number in the variable. As in a parametric answer.
 

Attachments

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Last edited:
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Seems to me there is some verbal description of the experiment missing at the start.
Are we to ignore rolling/spin?
As the spring expands from AA' to AO, is the force in the spring increasing, decreasing, or staying the same?
In the chart, which energy does E refer to? Is it just the energy in the ball (PE+KE) or the energy of the whole system, or something else?
You have calculated the velocity of the ball at O (assuming not rolling). What will be the speed at C? What dynamical equations do you know for the flight of the ball after C?
 
We are to ignore the rolling/spinning.
We assume that while the spring expands the force is staying the same.
In the chart, E refers to Mechanic Energy (Ep+Ek).
The speed at C should be 5 m/s,
and the afterwards I suppose it's to be projectile motion
 
harelori said:
We are to ignore the rolling/spinning.
We assume that while the spring expands the force is staying the same.
You're told that? Please post all the text describing the experiment.
In the chart, E refers to Mechanic Energy (Ep+Ek).
Yes, but just of the ball or of the whole system (i.e. including the spring)?
The speed at C should be 5 m/s,
and the afterwards I suppose it's to be projectile motion
Yes.
 
The whole system I suppose, you think you can you help me solve it?
 

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