# Forces and Motion Challenging Qs!

1. Mar 27, 2004

Assume that the Earth is a perfect sphere of diameter 1.274 X 10^7 m. If an object has a weight of 100 N while on a scale at the south pole, how much will it weigh at the equator? Assume that the equatorial spin speed, v = 465 m/s.

2. Mar 27, 2004

### enigma

Staff Emeritus

Forum rules state that you should at least attempt the problem before you ask for help on a problem.

If you have attempted them, please post what you've tried, so we can find where your misunderstandings or confusions lie.

Us doing the problem for you isn't going to help you learn it.

3. Mar 27, 2004

### ShawnD

Gravity pulls stuff towards earth. Velocity of earth tries to throw away from earth. Weight at the poles is due to 100% gravity.

weight at equator = 100N - mv^2/r

4. Mar 31, 2004

Plzz helpp

I tried this question the way i was told to..but i dunt think it works..plz help

Variables:
r = 1.274 X 10^7 m
v = 465 m/s
Weight = 100N at South Pole
Mass = F / g = 100N / 9.8 = 10.2kg

Gravity pulls stuff towards earth. Velocity of earth tries to throw away from earth. Weight at the poles is due to 100% gravity.

Weight at equator = 100N - mv^2/r
= 100N – (10.2kg)(465 m/s)^2 / 1.274 X 10^7 m
= 100N – 2205495 / 1.274 X 10 ^7 m
= -2205395 / 1.274 X 10 ^7
= -0.173N
Therefore the weight of the object at the equator is –0.173N?????

5. Mar 31, 2004

### ShawnD

Using the numbers you gave, I get 99.82688422

6. Mar 31, 2004