Answer:
Speed of water, v = 4.2 m/s
Explanation:
Given that,
Diameter of the tank, d = 17 cm
It is placed at a height of 90 cm, h = 0.9 m
We need to find the speed at which the water exits the tank through the hole. It can be calculated using the conservation of energy as :



v = 4.2 m/s
So, the speed of water at which the water exits the tank through the hole is 4.2 m/s. Hence, this is the required solution.
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Answer:
Decreased by a factor of 4.5
Explanation:
"We have Newton formula for attraction force between 2 objects with mass and a distance between them:

where
is the gravitational constant on Earth.
are the masses of the object and Earth itself. and R distance between, or the Earth radius.
So when R is tripled and mass is doubled, we have the following ratio of the new gravity over the old ones:




Since
and 

So gravity would have been decreased by a factor of 4.5
Answer:
The change in gravitational potential energy of the hiker = 2869685 J
Explanation:
Potential Energy: This is the energy possessed by a body, due to its change in position in the gravitational field. The unit of potential energy is Joules (J)
From the question,
Change in gravitational potential energy = Energy of the hiker at the top of Mt. Whitney - Energy of the hiker at the floor of Death valley.
ΔEp = mgh₂ - mgh₁
ΔEp = mg(h₂-h₁)........................... Equation 1
Where ΔEp = change in Potential Energy of the hiker, m = mass of the hiker, g = acceleration due to gravity, h₁ = lowest point in Death valley, h₂ = Elevation of Mt. Whitney.
Given: m = 65.0 kg, h₁ = -85 m ( because is a valley), h₂ = 4420 m,
Constant: g = 9.8 m/s²
Note: The h₁ is negative because is below sea level.
Substituting into equation 1
ΔEp = 65×9.8×[4420-(-85)]
ΔEp = 637(4420+85)
ΔEp = 637(4505)
ΔEp = 2869685
ΔEp = 2869685 J.
Thus the change in gravitational potential energy of the hiker = 2869685 J