Newton's Second Law for Translation and Rotation

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SUMMARY

This discussion focuses on the application of Newton's Second Law (N2L) in both translational and rotational contexts. Participants analyze various scenarios involving a low-friction pulley and a spinning ball, determining the appropriate application of N2L for each case. Key conclusions include the necessity of using N2L for rotation when calculating angular acceleration and recognizing that spinning does not significantly alter the maximum height of a thrown ball when applying N2L for translation. The consensus is that understanding the context of motion is crucial for accurate problem-solving.

PREREQUISITES
  • Newton's Second Law for Translation (N2L for Translation)
  • Newton's Second Law for Rotation (N2L for Rotation)
  • Basic principles of kinematics
  • Understanding of angular acceleration
NEXT STEPS
  • Study the relationship between angular acceleration and torque in rotational dynamics.
  • Explore the effects of spinning on projectile motion and its implications in kinematics.
  • Learn about the Bernoulli effect and its relevance to spinning objects in fluid dynamics.
  • Investigate real-world applications of N2L in engineering and physics problems.
USEFUL FOR

Students and professionals in physics, mechanical engineering, and anyone interested in the principles of motion and dynamics, particularly in relation to translational and rotational systems.

BayRan
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Homework Statement
For each of the situations below, determine which forms of Newton's second law (N2L) are appropriate.
Relevant Equations
Conceptual ideas.
Answer choices: N2L for Translation, N2L for Rotation, Both, Either1. You are asked to find the angular acceleration of a low-friction pulley with a given force exerted on it.

My solution = N2L for rotation

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2. You are asked to find the angular acceleration of a low-friction pulley due to a mass hanging from it by a rope.

My solution = Both

5.png


3. You are asked to determine the maximum height of a spinning ball that is thrown upwards.

My solution = Both

2.png


4. You are asked to calculate the time it takes a ball to roll down an inclined plane.

My solution = Both

3.png


5. You are asked to find the tangential acceleration of a small satellite in a circular orbit that results from it firing its thruster.

My solution = Both

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6. You are asked to determine the oribtal period of a small satellite around Earth.

My solution = N2L for translation

1.png
Besides the first two, I'm really just guessing based on my intuition. Please help.
 
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Let's start with #3. You were asked to find the max height that the ball get to. Why should the fact that it is spinning matter? Did you have to include the spinning part when you solve such a problem? I'm assuming that this is elementary kinematics, and that you're not including Bernoulli effect due to the spinning ball moving through air.

Zz.
 
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ZapperZ said:
Let's start with #3. You were asked to find the max height that the ball get to. Why should the fact that it is spinning matter? Did you have to include the spinning part when you solve such a problem? I'm assuming that this is elementary kinematics, and that you're not including Bernoulli effect due to the spinning ball moving through air.

Zz.

That's true. I had always imagined that the ball would be spinning when someone throws it, but I assumed something would change when we apply N2LR. I changed my answer to N2L for translation.
 

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