- #1
Jessibaca
- 5
- 0
How do you calculate average force? Where does time fit in?
How do you calculate average force?
- Context: High School
- Thread starter Jessibaca
- Start date
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- Tags
- Average Average force Force
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Discussion Overview
The discussion revolves around the calculation of average force, particularly how it relates to time and the conditions under which it can be determined. Participants explore various methods for calculating average force based on different available data, including graphs and kinematic variables.
Discussion Character
- Exploratory
- Technical explanation
- Mathematical reasoning
- Debate/contested
Main Points Raised
- One participant suggests calculating average force using the area under the force-time graph, indicating that this area represents the product of average force and total time.
- Another participant inquires about calculating average force when only initial and final velocities, mass, and time are known, seeking a relevant equation.
- A response indicates that if force is constant, one can find acceleration using the equation \(V_f = V_0 + at\) and subsequently calculate force using \(\Sigma F = ma\).
- However, a later reply challenges the assumption of constant force, stating that the acceleration used in the calculation is actually average acceleration, which may not imply constant acceleration.
- Another participant states that average force can also be expressed as \(F_{average} = \frac{m(v-u)}{t}\), where \(u\) is the initial velocity and \(v\) is the final velocity.
- It is noted that average acceleration can be defined as the change in velocity divided by the time taken, regardless of the smoothness of the velocity change.
Areas of Agreement / Disagreement
Participants express differing views on whether the force is constant or variable, leading to multiple competing approaches for calculating average force. The discussion remains unresolved regarding the implications of these differing assumptions.
Contextual Notes
There are limitations regarding the assumptions made about the constancy of force and acceleration, as well as the dependence on the specific data available (e.g., graphs versus kinematic variables). The discussion does not resolve these uncertainties.
- #2
Chen
- 976
- 1
If you have the graph of the force F as a function of time t, you first need to calculate the area below the graph, which is equal to the product of the average force and the total time:
[tex]\int _{t = 0} ^{\Delta t}Fdt = F_{avg}\Delta t[/tex]
See the attachment for an example. The red graph signfies the average force. The areas below the red graph and the blue graph need to be the same.
[tex]\int _{t = 0} ^{\Delta t}Fdt = F_{avg}\Delta t[/tex]
See the attachment for an example. The red graph signfies the average force. The areas below the red graph and the blue graph need to be the same.
Attachments
- #3
Jessibaca
- 5
- 0
Avg F
I don't have a graph. I have initial/final velocity, mass and time. Is there an equation for Average Force?
I don't have a graph. I have initial/final velocity, mass and time. Is there an equation for Average Force?
- #4
Chen
- 976
- 1
Then the force is constant... first find the acceleration of the body. Use this formula:
[tex]V_f = V_0 + at[/tex]
And then when you have the acceleration and the mass it's easy to find the force:
[tex]\Sigma F = ma[/tex]
[tex]V_f = V_0 + at[/tex]
And then when you have the acceleration and the mass it's easy to find the force:
[tex]\Sigma F = ma[/tex]
- #5
jcsd
Science Advisor
Gold Member
- 2,113
- 13
The force is not necessarily constant Chen, the 'a' (i.e. acceleration) in your first equation is infact the average accelartion (from the data set given it is impossible to deterimne whether a is constant or not).
Chen has alreday given you the correct equations, which can be given as:
[tex]F_{average} = \frac{m(v-u)}{t}[/tex]
where u is the initial velocity and v the final velocity
Chen has alreday given you the correct equations, which can be given as:
[tex]F_{average} = \frac{m(v-u)}{t}[/tex]
where u is the initial velocity and v the final velocity
- #6
JohnDubYa
- 468
- 1
The average force is mass times the average acceleration.
The average acceleration is simply the change in velocity divided by the time it took to change the velocity, regardless of whether the change is smooth or not.
The average acceleration is simply the change in velocity divided by the time it took to change the velocity, regardless of whether the change is smooth or not.
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