# Unit conversion proof ?

Show that 1 lb = 4.448 N

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- stanschimLv 71 month agoFavorite Answer
1 lb x (1 kg / 2.2 lb) = 0.4545...kg

F = mg = (0.4545...)(9.81) = 4.4591 N

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- billrussell42Lv 71 month ago
it's not exactly equal, only an approximation

1 US lb = 0.4535924 kg

this is in the definition of US pound, which is defined as 453.59237 g

multiply that by the value of g to get newtons. But g varies a bit over the surface of the earth. The usual approximation is 9.81 N/kg

0.4535924 kg x 9.81 N/kg = 4.450 N, but I'd round it to 4.45 N.

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