If you try opening a door by pushing too close to the side where the hinges are, you may find it difficult to push open. Suppose

you are trying to open a door that is 75 cm wide. (Hint: To solve this one, remember the example problem in the lesson about the MA of the broom). a. If you push on the door at a point 15 cm away from the hinges, what is the mechanical advantage? b. What is the best mechanical advantage that you can obtain for any door that you simply push open? Your answer:

Physics

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Steel blocks A and B, which have equal masses, are at TA = 300 oC and T8 = 400 oC. Block C, with mc - 2mA, is at TC = 350 oC. Bl

serg [3582]

Answer:

b) TA = TB = TC

Explanation:

When the blocks are brought into contact and isolated from the environment, they will exchange heat until they achieve thermal equilibrium.
During this exchange, the hotter body will lose heat, which will be gained by the cooler body.
The equilibrium state will be established once this equation is satisfied:

$\Delta Q = c_{st}* m_{A} * (T_{fin} - T_{0A} ) = c_{st}* m_{B} * (T_{0B} - T_{fin} )$

Substituting the initial temperatures T₀A = 300º C and T₀B = 400ºC, while simplifying for equal block masses mA = mB, enables us to solve for the final temperature, Tfin:

$(400 \ºC - T_{fin}) = (T_{fin} - 300 \ºC) \\ \\ 2* T_{fin} = 700\ºC\\ \\ T_{fin} = 350\ºC$

At equilibrium, when both blocks combine, they will yield a uniform final temperature of 350ºC.
When block C, also at this temperature, makes contact, all three blocks will simultaneously reflect this final temperature of 350 ºC.
Therefore, option b) is correct.

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