A 2.0-kg block slides on a rough horizontal surface. A force (magnitude P = 4.0 N) acting parallel to the surface is applied to
1 answer:
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The distance covered by car is equal to (assuming it is moving by uniform motion) the product between the car's speed and the time of the car ride, 4 h:
where
is the car's speed
is the duration of the car ride
Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:
The total distance covered is S=255 km, which is the sum of the distances covered by car and train:
which becomes
(1)
we also know that the train speed is 5 km/h greater than the car's speed:
(2)
If we put (2) into (1), we find
and if we solve it, we find
So, the car speed is 20 km/h and the train speed is 25 km/h.
where
Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:
The total distance covered is S=255 km, which is the sum of the distances covered by car and train:
which becomes
we also know that the train speed is 5 km/h greater than the car's speed:
If we put (2) into (1), we find
and if we solve it, we find
So, the car speed is 20 km/h and the train speed is 25 km/h.
Answer:
Red photons have the least amount of energy
Explanation:
The relationship between the photon energy and the color of light is given by:
where
E is the energy
h is the Planck constant
c is the speed of light
is the wavelength (which determines the color of light)
As we see from the equation, energy and wavelength are inversely proportional: this means that the longer the wavelength, the lower the energy, and viceversa.
Among the colors in the visible light spectrum, red is the color with longest wavelength (620-750 nm) and violet is the color with shortest wavelength (380-450 nm). This means that red photons have the least amount of energy, while violet photons have the greatest amount of energy.
So the correct choice is
Red photons have the least amount of energy