An observer sees a full moon in the night sky. What will the Moon's phase be 10 days later?
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Missing part in the text of the problem:
"<span>Water is exposed to infrared radiation of wavelength 3.0×10^−6 m"</span>
First we can calculate the amount of energy needed to raise the temperature of the water, which is given by
where
m=1.8 g is the mass of the water
is the specific heat capacity of the water
is the increase in temperature.
Substituting the data, we find
We know that each photon carries an energy of
where h is the Planck constant and f the frequency of the photon. Using the wavelength, we can find the photon frequency:
So, the energy of a single photon of this frequency is
and the number of photons needed is the total energy needed divided by the energy of a single photon:
"<span>Water is exposed to infrared radiation of wavelength 3.0×10^−6 m"</span>
First we can calculate the amount of energy needed to raise the temperature of the water, which is given by
where
m=1.8 g is the mass of the water
Substituting the data, we find
We know that each photon carries an energy of
where h is the Planck constant and f the frequency of the photon. Using the wavelength, we can find the photon frequency:
So, the energy of a single photon of this frequency is
and the number of photons needed is the total energy needed divided by the energy of a single photon:
Answer:
Explanation:
In order to solve this problem, we must first do a drawing of the situation (see attached picture).
When the brakes of the car were applied, we can see that there was only one horizontal force affecting the vehicle's movement, which was the force of friction. When analyzing the free body diagram we can apply Newton's laws to determine the equations we will use to solve this.
so:
-f=ma
we also know that:
so
we can now solve for the acceleration, so we get:
we don't know what the normal force is, so we can find it out by analyzing the vertical forces applied to the car:
so we get:
N-W=0
which means that:
N=W
we also know that:
W=mg
so
N=mg
we can substitute this into the first equation so we get:
which simplifies to:
we can now substitute the provided data:
which yields:
once we got the acceleration, we can use kinematics formulas to solve this, we got the following formula:
we know the final velocity must be zero, since that's where the car got to a stop, so the formula then becomes:
we can now solve for the initial velocity, which yields:
so we can now substitute the daa we know, so we get:
so we get:
So from this we know that the velocity of the car must have been of at least 29.68m/s when the brakes were applied.