Answer:
C- Choosing variables and controls
Explanation:
Correct on edge.
If it produces 20J of light energy in a second, then that 20J is the 10% of the supply that becomes useful output.
20 J/s = 10% of Supply
20 J/s = (0.1) x (Supply)
Divide each side by 0.1:
Supply = (20 J/s) / (0.1)
<em>Supply = 200 J/s </em>(200 watts)
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Here's something to think about: What could you do to make the lamp more efficient ? Answer: Use it for a heater !
If you use it for a heater, then the HEAT is the 'useful' part, and the light is the part that you really don't care about. Suddenly ... bada-boom ... the lamp is 90% efficient !
The answer for this problem would be:
Assuming non-relativistic momentum, then you have:
ΔxΔp = mΔxΔv = h / (4)
Δv = h / (4πmΔx)
m ~ 1.67e-27 h ~ 6.62e-34,Δx = 4e-15 -->
Δv ~ 6.62e-34 / (4π * 1.67e-27 * 4e-15) ~ 7,886,270 m/s ~ 7.89e6 m/s
That's about 1% of the speed of light, the assumption that it's non-relativistic.
Because it does not produce waste, thus it doesn't harm the environment. also renewable sources are infinite.
120 km/3 hours. 40/1=?/3 1x3=3 hours so 40x3=120 km
