Well, we know that the total energy in a closed system remains constant.
The problem with the story of Eva is that she is not in a closed system.
If the dark room were really a closed system, then she could press the
button or turn the switch all day, and the lamp could not light. It needs
electrical energy coming in from somewhere in order to turn on.
Let's say that Eva used her arm muscles to strike a match and light the
candle on the table. Then we would have have food energy, muscle
energy, chemical energy in the match, chemical energy in the candle,
heat and light energy coming out of the candle, heat energy soaking into
her hand, light energy bouncing off of the book and into her eyes ... all
going on during the story, and the sum total of all of them would remain
constant.
New Moon appears completely dark
D.) It is an "Element".
[ Element cannot be separated by any means ]
Hope this helps!
Answer:
300J
Explanation:
Given parameters:
Constant force = 15N
Distance = 20m
Unknown:
Work done = ?
Solution:
Work done is the force applied to move a body through a particular distance.
Work done = Force x distance
So;
Work done = 15 x 20 = 300J
