an ldr's resistance changes with light intensity, while a thermistor's resistancce changes with temperature.
in dark, ldr's resistance is large and in the day/light ldr's resistance is small.
at low temperature, thermistor's resistance is large, while at large temperature it resistance is small.
in an ldr resistance increases as light intensity falls, while in a thermistor resistance falls as temperature falls.
the chemical reaction of cavendish involving zinc would be a reaction between hydrochloric acid and zinc yielding zinc chloride and hydrogen gas.
average speed = (total distance covered) / (time to cover the distance)
total distance = (80m) + (125m) + (45m) = 250 meters
overall time = 10 minutes
average speed = (250 meters) / (10 minutes)
average speed = 25 meters/minute
since we're only looking for average speed and not velocity, we don't care about any of the directions, and we don't need to calculate mary's displacement.