Gravitational Attraction at Equator

[Felin]

The weight of a person at the equator, as determined by a spring balance, is 725N.

By how much does this differ from the true force of gravitational attraction at the same point? Assume that the Earth is spherically symmetric.

This question is on a section that we havn't even done yet so I am completely lost as to what to do to figure this one out.

 

[Dorothy Weglend]

There is an additonal force at the equator that isn't present at the poles. Once you realize what that is, you can calculate its magnitude.

Dorothy