Question 1

Why is apparent weight different from true weight at the equator?

Accepted Answer

At the equator, objects move in a circle due to Earth's rotation, requiring centripetal acceleration toward the rotational axis. The spring scale reading (apparent weight) equals true weight minus the centripetal force needed for this circular motion. At the poles, centripetal force is zero, so apparent weight equals true weight.

Question 2

How does Earth's rotation affect the centripetal force on an object?

Accepted Answer

Centripetal force is proportional to Earth's radius and the square of its angular speed. Since Earth's angular speed is relatively small, the centripetal force is also small. At the equator, this force accounts for only a 0.34% difference between true and apparent weight, making it a minor correction.

Question 3

What forces act on an object suspended from a scale at the equator?

Accepted Answer

Three forces act on the object: gravitational force directed toward Earth's center, tension force in the spring directed away from the center, and centripetal force directed toward the rotation axis. The tension force (apparent weight) balances the gravitational force minus the centripetal force requirement.

Question 4

How fast would Earth need to rotate for objects at the equator to feel weightless?

Accepted Answer

For objects at the equator to feel weightless, the centripetal force would need to equal the gravitational force. Calculations show Earth's orbital period would need to be only 84 minutes instead of 24 hours. This demonstrates how slowly Earth actually rotates relative to what would be required for weightlessness.

Question 5

Why do objects at the poles experience no centripetal force effect?

Accepted Answer

At the poles, objects do not move in a circle around Earth's rotational axis; they remain stationary relative to the axis. Since there is no circular motion, no centripetal acceleration is needed. Therefore, apparent weight equals true weight at the poles.

Question 6

What is the relationship between tension force and apparent weight on a scale?

Accepted Answer

The tension force in the spring scale equals the apparent weight of the object. This reading represents the normal force preventing the object from falling through the scale. At the equator, this tension is less than the gravitational force because some gravitational force provides the necessary centripetal acceleration.

Question 7

How does variation in acceleration due to gravity relate to Earth's rotation?

Accepted Answer

Earth's rotation causes variation in acceleration due to gravity near the earth s surface by reducing the effective gravitational acceleration at the equator. The centripetal acceleration required for circular motion at the equator reduces the net downward acceleration, making objects appear lighter on a scale compared to the poles.

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