8) The height of the shelf is 2.04 m
9) The gravitational potential energy is 100 J
Explanation:
8)
The gravitational potential energy of an object is given by:
[tex]PE=mgh[/tex]
where
m is the mass of the object
g is the acceleration of gravity
h is the heigth of the object, relative to the ground
For the object in this problem, we have
m = 10 kg
[tex]g=9.8 m/s^2[/tex]
And we know that
PE = 200 J
Therefore we can re-arrange the formula to solve for h, the heigth of the object:
[tex]h=\frac{PE}{mg}=\frac{200}{(10)(9.8)}=2.04 m[/tex]
9)
As before, the gravitational potential energy of the object is given by:
[tex]PE=mgh[/tex]
where in this case, we have:
m = 10 kg is the mass of the object
h = 2.04 m is the height of the object from the ground
While in this case, the acceleration of gravity on this planet is
[tex]g=4.9 m/s^2[/tex]
Substituting,
[tex]PE=(10)(4.9)(2.04)=100 J[/tex]
Learn more about potential energy:
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