Today in class, we did the quiz first. in the quiz we use the equation q=mLto find the heat of evaporation and q=cm(T_f-T_i) to find the heat of boiloing.
this photo is about the third question in the quiz and ask two uncertainty.
Then we start the experiment about the first law of thermodynamics. The scond photo is that we find the work done during volume changes. and the two graphs in the second photos shows that the work done euqals the area under the curve.
these two photos show us that when we put the flask to put into hot water, the volunme of air in the work drum will be bigger , but when we put the flask into ice water and find the volume of air in the work drum will be smaller.
in the photo, we use the equation to find the internal energy of air.
then we did an exercise to find the work done of copper bar. and we use the equation of V_change= V_i*B* (T_f-T_i)and W=P*V_0*B*(T_f-T_i)
these two photos tell us if the temperature or pressure are increasing , the motion of atoms becomes more violent/.
in this photo, we find the speed v of a molecule is related to the velocity components v-x,v_y and v_z by v^2=v_x^2+v_y^2+v_z^2.and we can find v^2=3v_x^2. in the second photo, we know that P=F/A=Nmv_x^2/V and we use v^2=3v_x^2 and find that P=Nmv^2/3V.
in this photo, we find the equation about T and E
in this photo, we find the relationship of molecular speeds and T.
in this photo, we find the P_i^(3/2)*V_i=P_f^(3/2)*V_f.
in this experiment, we need to find the final T of cotton is 711K
conclusion:
Today
in class, we did a quiz first. Then we learn the first law of thermodynamics. We
know that U=Q-W. and we know how to use W=(v2-v1)when pressure is constant.
Then we figure out the Kinetic molecular model of an ideal gas and relationship of
molecular speeds and T.
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