Ice cubes are added to an insulated cup of hot water. As a result, the temperature of the water decreases and the ice melts. What statement best explains the change in entropy of the system, which is the combination of water and ice cubes, on a molecular level? a. The entropy of the system decreases, because the translational and vibrational motion of molecules in the liquid water decrease during collisions with molecules in the ice.
b. The entropy of the system remains unchanged, because the same amount of heating and cooling occur.
c. The entropy of the system increases, because the energy gained by the ice molecules is greater than the energy lost by the liquid water molecules.
d. The entropy of the system increases, because the disorder caused by the change in state from solid to liquid water causes more disorder than liquid water cooling causes order.

Many machines- including inclined planes such as ramps- increase the strength of the force put into the machine but decrease the distance over which the force is applied.

A150 w lamp emits light of wavelength 590 nm uniformly in all directions. what is the photon flux (photons per unit area per unit time) on a small screen at a distance 2.3 m from the lamp? assume the photons are uniformly distributed over the surface of a sphere of radius 2.3 m.

Fft review: linspace, fs, fftshift, nfft 1. generate one second of a cosine of w,-10hz sampled at f, = 100hz and assign it to x. define a tt as your time axis 2. take 64 points fft. 3. as you remember, the dft (which the fft implements) computes n samples of s2t where k-0,1,2, n -1. plot the magnitude of this 64-points fft at range 0 to 63, what do you think of this graph? 4â·to get the x-axis into a hz-frequency form, plot this 64-points fft between-50 to 50 (the 100hz sampling rate) and have n-points between them. 5. according to your figure, what frequency is this cosine wave at? 6. remember that the fft is evaluating from 0 to 2ď€. we are used to viewing graphs from-ď€ to ď€. therefore, you need to shift your graph. 7. now according to your shifted graph. what frequency is this at? 8. note that the spikes have long drop-offs? try a 1024-point dft. note that the peak is closer to 10 and the drop-off is quicker. although, now sidelobes are an issue