Explanation:
Efficiency is defined as the ratio between the useful output over the total amount consumed.
The fan does 500W of useful work while wasting 300 W. The total power consumption is 800 W (500 + 300).
You are riding in a hot air balloon that, relative to the ground, has a velocity of 6.0 m/s due east. You see a hawk moving dire
1 answer:
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The area of the circle with radius r is
A = πr²
The rate of change of area with respect to time is
The rate of change of the radius is given as
Therefore
When r = 10 ft, obtain
Answer: - 40π ft²/s (or - 127.5 ft²/s)
A = πr²
The rate of change of area with respect to time is
The rate of change of the radius is given as
Therefore
When r = 10 ft, obtain
Answer: - 40π ft²/s (or - 127.5 ft²/s)
1) 29.4 N
The force of gravity between two objects is given by:
where
G is the gravitational constant
M and m are the masses of the two objects
r is the separation between the centres of mass of the two objects
In this problem, we have
(mass of the Earth)
(mass of the box)
(Earth's radius, which is also the distance between the centres of mass of the two objects, since the box is located at Earth's surface)
Substituting into the equation, we find F:
2)
Let's now calculate the ratio F/m. We have:
F = 29.4 N
m = 3.0 kg
Subsituting, we find
This is called acceleration of gravity, and it is the acceleration at which every object falls near the Earth's surface. It is indicated with the symbol .
We can prove that this is the acceleration of the object: in fact, according to Newton's second law,
where a is the acceleration of the object. Re-arranging,
which is exactly equal to the quantity we have calculated above.