What are the forces acting on a boat crossing a still lake at a constant speed?

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Homework Help Overview

The discussion revolves around a physics problem involving a model boat crossing a still lake at a constant speed. The subject area includes forces, specifically friction and buoyancy, as well as principles such as Newton's laws and Archimedes' principle.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between forces acting on the boat, questioning how to determine the friction force and the buoyancy force. Some participants attempt to apply relevant equations and principles, while others seek clarification on the role of gravity in the scenario.

Discussion Status

The discussion is active, with participants offering guidance on the relationships between forces. There is an emphasis on understanding the balance of forces when the boat is moving at a constant velocity, and some participants are questioning their assumptions about the problem setup.

Contextual Notes

Participants note that the problem involves a model boat with a specified mass and thrust, and there is a focus on understanding the implications of constant speed in relation to the forces acting on the boat.

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Homework Statement



Hi could some one point me in the right direction for both parts of these questions, I am electrical biased so this is all new to me.

A model boat off mass 25 Kg is crossing a still lake at a constant speed, in a straight line. The engine is propelling the boat along with 30 force.

a) What is the size of the total friction force opposing the boat?
b) How much buoyancy force is the boat producing?

Homework Equations



F=ma ?

The Attempt at a Solution


 
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a Sum Forces = mass * acceleration
b Archimedes Principle
 
for a) do i rearrange the formula and divide 30n/25kg = 1.2 m/s ?

for b) I now understand that the forces acting down must equal the forces acting up. does gravity come into this scenario?
 
a) Don't be silly. The problem asks what is the magnitude of the friction force opposing the motion of the boat. Ask yourself, if the boat is traveling at a constant velocity (it does not matter what this velocity is), what forces are acting on the boat? What must their magnitudes be relative to one another? You are given the thrust produced by the engine (30 N).

b) Obviously, if the weight of water displaced by the boat is equal to the weight of the boat, according to Archimedes, gravity is involved.
 

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