Calculating Torque for a Particle in an xy Plane

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SUMMARY

The discussion focuses on calculating the torque acting on a particle moving in an xy plane, specifically at time t = 2.1 seconds, given that the magnitude of its angular momentum is expressed as 2.5t² kg·m²/s³. The correct formula for torque is established as torque = dL/dt. The user initially calculated the derivative of the angular momentum incorrectly, arriving at 10.5 without considering the unit vector, which is crucial for obtaining the correct torque value.

PREREQUISITES
  • Understanding of angular momentum and its mathematical representation.
  • Familiarity with calculus, specifically differentiation.
  • Knowledge of unit vectors in physics.
  • Basic concepts of torque in rotational dynamics.
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  • Review the principles of angular momentum and its derivatives.
  • Study the application of unit vectors in torque calculations.
  • Practice problems involving torque and angular momentum in two-dimensional motion.
  • Explore the relationship between torque and rotational motion dynamics.
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Students studying physics, particularly those focusing on mechanics, as well as educators looking for examples of torque calculations in rotational dynamics.

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Homework Statement



A particle is to move in an xy plane, clockwise around the origin as seen from the positive side of the z axis. In unit-vector notation, what torque acts on the particle at time t = 2.1 s if the magnitude of its angular momentum about the origin is 2.5t2 kg·m2/s3

Homework Equations



torque = dL/dt

The Attempt at a Solution



I tried taking the derivative of 2.5*t2 and then I inserted t.

2*2.5*2.1 = 10.5 but this is not the correct answer and I'm not sure why.
 
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Did you put in just the number alone or the number with the unit vector?
 

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