Did I Neglect the Skier in the Resistive Force Calculation?

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    Force Resistive force
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Discussion Overview

The discussion revolves around the calculation of total resistive force experienced by a boat with a skier being towed behind it. Participants explore the implications of the power output of the boat's engine and the relevance of the masses involved in the calculation.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant calculates the resistive force using the formula Power = Force x Velocity, arriving at a force of 7000N, but expresses doubt about neglecting the skier's mass.
  • Several participants assert that the masses of the boat and skier are irrelevant to the calculation of resistive force based on the provided power output.
  • Another participant confirms that the 140kW is the total power, suggesting that the initial calculation is acceptable.

Areas of Agreement / Disagreement

There is a lack of consensus regarding the relevance of the skier's mass in the calculation, with some participants asserting it is irrelevant while others express uncertainty about this assumption.

Contextual Notes

The discussion does not resolve the implications of neglecting the skier's mass, nor does it clarify the assumptions regarding the total power output and its application to the resistive force calculation.

Userxy
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Hi,
Imagine a boat with a skier behind it (connected with a rope).

Mass of boat=2000Kg
Mass of skier=80Kg
At 20m/s the boat engine has a power output of 140kW

Calculate the total resistive force.

Power=FxV
140000W=Fx20m/s
F=7000N

Is the answer right ? I doubt my answer, even if its really easy, because I totally neclected the skier.

Thanks!:wink:
 
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It's correct. The masses are irrelevant.
 
Paul Eccles said:
It's correct. The masses are irrelevant.
Okay, Thank you!
 
I think that 140kW is the total power. So is ok.
 

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