Answer:
efficiancy=40 percent
Explanation:
efficiency=energy output/energy input×100
efficiancy=8J/20J×100
efficiancy=0.4×100
efficiancy=40 percent
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D.<span>Wave 3 resulted from constructive interference, and Wave 4 resulted from destructive interference.
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the answer is b) magnetic current
Answer : The specific heat capacity of the alloy 
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.
where,
= specific heat of alloy = ?
= specific heat of water = 
= mass of alloy = 21.6 g
= mass of water = 50.0 g
= final temperature of system = 
= initial temperature of alloy = 
= initial temperature of water = 
Now put all the given values in the above formula, we get
Therefore, the specific heat capacity of the alloy
