Two objects perform the same task. One has thousands of moving parts while the other has no moving parts. What are they?.
1 answer:
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Answer:
Explanation:
<u>Net Force</u>
The Second Newton's law states that an object acquires acceleration when an external unbalanced net force is applied to it.
That acceleration is proportional to the net force and inversely proportional to the mass of the object.
It can be expressed with the formula:
Where
Fn = Net force
m = mass
The m=200 kg crate is pushed horizontally with a force Fa=700 N. The friction force opposes motion and a horizontal net force appears causing the acceleration.
The forces on the vertical direction are in balance since the crate does not accelerate in that direction, thus the weight and the normal force are equal:
N = W = mg
The friction force can be calculated by using the coefficient of friction μ:
Calculating the normal force:
N = 200 * 9.8 = 1,960 N
The friction force is:
The horizontal net force is:
Finally, the acceleration is computed:
Answer:
Explanation:
According to the Stefan-Boltzmann law for real radiating bodies:
(1)
Where:
is the energy radiated (in Watts)
is the Stefan-Boltzmann's constant.
is the Surface area of the body
is the effective temperature of the body (its surface absolute temperature) in Kelvin
is the body's emissivity
On the other hand, we are told the human body is roughly approximated to a cylinder of length and circumference
.
The circumference of a circle is: where
is the radius. Hence
.
Now we have to input this value for in the Area of a cylinder formula:
(2)
Substituting (2) in (1):
(3)
Finally: