find local g
a = -g
v = Vi - g t
h = Hi + Vi t - .5g t^2
here Hi = 1
Vi = 0
so
h = Hi - .5g t^2
Hi = 1
h = 0 at ground
0 = 1 - .5 g t^2
.5 g (.7)^2 = 1
.5 * .49 g = 1
.49 g = 2
g = 4.08 m/s^2
weight = m g = 60 * 4.08 Newtons
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r = 1.6*10^6
Newton - law of gravity
Weight = F = G M m/r^2 where G = 6.67*10^-11
60 * 4.08 = 6.67*10^-11 * M * 60 * 10^22 /[ 6.67^2]
note the 60 cancels of course
A 60kg astronaut on a distant planet drops a fork and discovers the fork takes 0.70s to drop 1.0m to the ground.
a) what is the weight of the astronaut on that planet?
b) if the planet has a radius of 1.6x10^6 m, what is it’s mass?
1 answer