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Ede4ka [16]
3 years ago
14

.A 0.2-kg aluminum plate, initially at 20°C, slides down a 15-m-long surface, inclined at a 30 angle to the horizontal. The forc

e of kinetic friction exactly balances the component of gravity down the plane so that the plate, once started, glides down at constant velocity. If 90% of the mechanical energy of the system is absorbed by the aluminum, what is its temperature increase at the bottom of the incline? (Specific heat for aluminum is 900J/kg⋅°C.)
a. 0.16 C°b. 0.07 C°c. 0.04 C°d. 0.03 C°
Physics
1 answer:
Ainat [17]3 years ago
7 0

To solve this problem, it is necessary to apply the concepts related to Work according to the Force and distance, as well as the concepts related to energy lost-or gained-by heat. Mathematically the energy corresponding to heat is given as:

Q = mC_p(\Delta T)

Where,

m = mass

C_p= Specific heat

\Delta T = Change in Temperature

At the same time the Work made by the Force and the distance is given as:

W = F*d \rightarrow W=mg*d

As the force is applied at an angle of 30 degrees, the efficient component would be given by the vertical then the work / energy would be determined as:

W = mg*dsin(30)

W = (15m)(0.2kg)(9.81)(sin30)

W = 13.24J

Now this energy is used to heat the aluminum. We can find the change at the temperature as follow:

Q = mC_p(\Delta T)

13.24 = (0.2)(900)(\Delta T)

\Delta T = 0.0736 \°C

Therefore the correct answer is B.

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First of all, we can calculate the frequency of the photon, which is related to the wavelength by the following equation:
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