Mechanics: Friction - Wheelbarrow Mass 8kg, Coeff. 0.6, Force 50N, Angle 30°

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    Friction Mechanics
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Discussion Overview

The discussion revolves around the mechanics of a gardener pulling a wheelbarrow with varying mass and the effects of friction. Participants explore the acceleration of the wheelbarrow under different conditions, specifically when additional weight is added and how it affects the forces at play.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant calculates the acceleration of the wheelbarrow with an initial mass of 8kg and finds it to be 1.29m/s².
  • Another participant notes that when the wheelbarrow's mass increases to 28kg (8kg + 20kg of soil), the normal force and thus the friction force will also increase.
  • Participants discuss the need to compare the updated friction force to the horizontal component of the applied force of 50N.
  • A calculation is presented where the new contact force is stated as 255N and the friction force as 153N, leading to an equation that suggests a negative acceleration of -3.92m/s², indicating that the wheelbarrow does not move.
  • Several participants agree that the horizontal component of the applied force is insufficient to overcome the maximum force of friction, resulting in no acceleration.

Areas of Agreement / Disagreement

Participants generally agree that with the increased mass of the wheelbarrow, the friction force becomes too great for the applied force to produce acceleration, leading to a consensus that the wheelbarrow does not move. However, the reasoning and calculations leading to this conclusion are discussed and refined without a definitive resolution on the exact values used.

Contextual Notes

Participants express uncertainty regarding the calculations of forces and acceleration, particularly in how the friction force is derived and compared to the applied force. There are also unresolved assumptions about the conditions under which the forces are calculated.

Who May Find This Useful

This discussion may be useful for students or individuals interested in understanding the dynamics of forces, friction, and acceleration in mechanical systems, particularly in practical applications involving weight changes and force angles.

Shah 72
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A gardener is pulling a wheelbarrow of mass 8kg from rest along rough horizontal ground. The coefficient of friction between the wheelbarrow and the ground is 0.6. The gardener provides a force of 50N at an angle of 30 degree above the horizontal as shown in the diagram.
a) Find the acceleration of the wheelbarrow
I got the ans for this a = 1.29m/s^2
b) what happens when the wheelbarrow had 20kg of soil in it and the gardener exerts the same force at the same angle?
I don't understand how to solve this.
 
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Shah 72 said:
A gardener is pulling a wheelbarrow of mass 8kg from rest along rough horizontal ground. The coefficient of friction between the wheelbarrow and the ground is 0.6. The gardener provides a force of 50N at an angle of 30 degree above the horizontal as shown in the diagram.
a) Find the acceleration of the wheelbarrow
I got the ans for this a = 1.29m/s^2
b) what happens when the wheelbarrow had 20kg of soil in it and the gardener exerts the same force at the same angle?
I don't understand how to solve this.
 
mass of the wheelbarrow is now 8+20 = 28 kg

normal force increases $\implies$ friction force will increase

compare the updated friction force to the horizontal component of the applied 50N force
 
skeeter said:
mass of the wheelbarrow is now 8+20 = 28 kg

normal force increases $\implies$ friction force will increase

compare the updated friction force to the horizontal component of the applied 50N force
Thank you. So the new contact force =255N and friction is 153N. By using F=m×a, 50cos30-153=28a, I get a=-3.92m/s^2. So since the acceleration is negative the wheel barrow doesn't move. Is this reasoning correct?
 
There is no acceleration ... the horizontal component of the applied force is not great enough to overcome the maximum force of friction.
 
skeeter said:
There is no acceleration ... the horizontal component of the applied force is not great enough to overcome the maximum force of friction.
Thank you !
 

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