The Earth's Rotational Speed: Where to Stand for Minimum Speed?

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SUMMARY

The Earth's rotational speed varies depending on the location on its surface, with the minimum tangential speed occurring at the poles, where rotational movement is negligible. A clock with hands moving at the same tangential speed is theoretically feasible but impractical due to the differing lengths of the hands, which would require complex mechanisms. Additionally, when larger diameter tires are mounted on a truck, the speedometer, calibrated for smaller tires, will read a speed greater than the actual linear speed due to the increased circumference. Lastly, while analyzing the angular acceleration of a fan's blades after shutdown, it is evident that the acceleration cannot be constant because the deceleration rate changes until the blades come to a complete stop.

PREREQUISITES
  • Understanding of Earth's rotational dynamics
  • Familiarity with rotational kinematics
  • Knowledge of angular and linear speed relationships
  • Basic principles of mechanical clocks and their components
NEXT STEPS
  • Research the physics of Earth's rotation and its effects on tangential speed
  • Explore the principles of rotational kinematics in detail
  • Study the relationship between tire diameter and speedometer readings
  • Investigate the mechanics of clock design, focusing on hand movement and tangential speed
USEFUL FOR

Physics students, mechanical engineers, and anyone interested in the principles of motion and rotational dynamics.

hatingphysics
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1) The Earth rotates once per day about its axis. Where on the Earth's surface should you stand in order to have the smallest possible tangential speed?

would it be on the top of axis since it will not move?

2) It is possible, but not very practical, to build a clock in which the tips of the second hand, the minute hand, and the hour hand move with the same tangential speed. Explain why it would be possible but not practical.

I have no idea here...i didn't even know this was possible?!3) Suppose that the speedometer of a truck is set to read the linear speed of the truck, but uses a device that actually measure the angular speed of the tires. If larger diameter tires are mounted on the truck, will the reading of the speedometer be correct? if not, will the reading be greater than or less than the true linear speed of the truck? Why?

No, because the diameter is more for the wheel which will give a larger speed compared to the linear speed. Is this true...i don't know what the right answer is.

4) The blades of a fan rotate more and more slowly after the fan is shut off. Eventually they stop rotating altogether. In such a situation we sometimes assume that the angular acceleration of the blades is constant and apply the equations of rotational kinematics as an approximation. Explain why the angular acceleration can never really be constant in this kind of situation.

is it because the speed of the fan turning off is changing till it stops?

5) Rolling motion is one example that involves rotation about an axis that is not fixed. Give three other examples. In each case, identify the axis of rotation and explain why it is not fixed.

i have no clue!
 
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hatingphysics said:
2) It is possible, but not very practical, to build a clock in which the tips of the second hand, the minute hand, and the hour hand move with the same tangential speed. Explain why it would be possible but not practical.

I have no idea here...i didn't even know this was possible?!
Think of the length of each hand.
 

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