A flashlight battery is hooked to a toy motor, and then the battery and the connections are sprayed with a water-proof coating. The battery is immersed in a beaker holding 100 mL of water. When the toy motor drives a device that raises a weight of 1.00 kg a distance of 10.0 m, the temperature of the water falls by 0.024 C. Assuming that the heat capacity of the battery is negligible compared to that of the water, calculate the change in the energy of the battery contents as a result of the chemical reaction that took place in the battery.
Work done by motor = (mass) * (g) * (height)
where g = gravitational constant = 10 m/s2
Work done by motor = (1.00 kg) * (10 m/s2) * (10.0 m)
Work done by motor = 100.0 J
heat lost by water = (mass water) * (specific heat water) * (temperature change)
heat lost by water = (100 g) * (4.184 J/g.oC) * (0.024 oC)
heat lost by water = 10.0 J
heat gained by motor = heat lost by water
heat gained by motor = 10.0 J
change in energy = heat gained - work done
change in energy = (10.0 J) - (100.0 J)
change in energy of the battery = -90.0 J
A flashlight battery is hooked to a toy motor, and then the battery and the connections...