Question

if pete (mass =90.00kg) weighs himself and finds that he weighs 30.0 pounds, how far away from the earth is he?

Answer 1

Here we know that mass of the person is 90 kg

His weight is given as 30 lbf

so here we can convert it into Newton as we know that

1 lbf = 4.45 N

Now from above conversion

$30 lbf = 30 \times 4.45 = 133.45 N$

now we can use this to find the gravity at this height

$mg = 133.45$

$90\times g = 133.45$

$g = 1.49 m/s^2$

now we know that with height gravity varies as

$g' = g(\frac{R}{R+H})^2$

$1.49 = 9.8(\frac{6.37\times 10^6}{6.37\times 10^6 + h})^2$

$h = 1.0 \times 10^7 m$

so above is the height from the surface of earth