no, it not useless. we still learn Bohr's model in HS n dats almost 200 yr old! while there may be new models, previous one is good for explaining the basics. it is also useful to learn previous model n see how our understanding improves over time.
<span>The specific heat (or the amount of heat required to raise the temperature of a unit mass of a substance by 1 degree Celsius) of copper is about 0.386 J/g/degree Celsius. This means that if we supply 0.386 J of energy to 1 gram of copper, its temperature will increase by 1 degree Celsius.</span>
The weight of the meterstick is:

and this weight is applied at the center of mass of the meterstick, so at x=0.50 m, therefore at a distance

from the pivot.
The torque generated by the weight of the meterstick around the pivot is:

To keep the system in equilibrium, the mass of 0.50 kg must generate an equal torque with opposite direction of rotation, so it must be located at a distance d2 somewhere between x=0 and x=0.40 m. The magnitude of the torque should be the same, 0.20 Nm, and so we have:

from which we find the value of d2:

So, the mass should be put at x=-0.04 m from the pivot, therefore at the x=36 cm mark.
Answer:
<u><em>Definition of spectral line: </em></u><em>one of a series of linear images formed by a spectrograph or similar instrument and corresponding to a narrow portion of the spectrum of the radiation emitted or absorbed by a particular source.</em>
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<u><em>Definition of Wavelength:</em></u><em> can be defined as the distance between two successive crests or troughs of a wave. It is measured in the direction of the wave. ... Wavelength is inversely proportional to frequency. This means the longer the wavelength, lower the frequency.</em>
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<em>So, the spectrum is the range of wavelength in visible light. While, wavelength is the length of a wave.</em>
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Explanation:
I hope this helps!
C.
Because it’s falling it has acceleration in the y direction. If you have acceleration, you usually also have velocity, and since kinetic energy is KE= Mv^2 you know you have it. It also has potential energy because it has some height to it, and PE= Mgh.