A warehouse conveyor belt is supplied with 1200 J during one cycle. The table shows the energy it transfers in ways that are not useful.
| Wasted energy transfer | Energy in J\mathrm{J}J |
|---|---|
| Heating by friction in the rollers | 300 |
| Heating in the wires | 180 |
| Sound | 120 |
Wires with a lower resistance are fitted. This reduces the heating in the wires to one third of its previous value. The energy supplied per cycle and the other two wasted transfers stay the same.
What is the efficiency of the conveyor belt after the new wires are fitted?
50%50\%50%
55%55\%55%
40%40\%40%
60%60\%60%