Calculate Paul's Speed with Work and Energy: Friction & Tension on a Mat

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SUMMARY

The discussion focuses on calculating the speed of Paul, a 13.0 kg child, after being pulled on a mat with a constant tension of 30.0 N at a 30-degree angle, while overcoming a friction coefficient of 0.180. The net force acting on the system was determined to be 5.73 N. To find Paul's speed after being pulled 2.60 m, participants advised using the work-energy principle, specifically calculating the work done by the net force and equating it to the change in kinetic energy to derive the final speed.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the work-energy theorem
  • Basic knowledge of friction and tension forces
  • Ability to perform calculations involving net force and mass
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  • Calculate work done using the formula: Work = Net Force x Distance
  • Learn about the work-energy theorem and its application in physics problems
  • Explore the relationship between kinetic energy and speed
  • Review examples of problems involving friction and tension forces in motion
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This discussion is beneficial for physics students, educators, and anyone interested in understanding the application of work and energy principles in real-world scenarios involving forces, friction, and motion.

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Susan's 13.0 kg baby brother Paul sits on a mat. Susan pulls the mat across the floor using a rope that is angled 30 degrees above the floor. The tension is a constant 30.0 N and the coefficient of friction is 0.180.

Use work and energy to find Paul's speed after being pulled 2.60 m


So far I found the forces acting on the system to be:

Y:
127.5N down due to gravity
15N up due to tension
112.5N normal force
X:
25.98 due to tension
-20.25 due to friction

So I get a net force of 5.73N which I thought if I divided by the mass of 13kg it would give me that speed, but that is wrong. I am stuck here guys.

Thanks in advance for the help
 
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Force divided by mass is acceleration.

The instructions say to use work and energy. Now that you have the net force, use that to calculate the work. And then use the change in kinetic energy to calculate the speed.
 

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