Athermometer is placed in water in order to measure the water's temperature period what would cause the liquid in the thermometer to rise?

The thermal energy of the water. Because the water is waaay above Absolute Zero (0K, or -273,15 C) it holds thermal energy or aka the temperature of the water. If the temperature of the water is higher than the one in the thermometer, the heat will 'flow' into the liquid (mostly mercury or modern, it is ethanol), causing the liquid to rise since it's volume increases. The same when te water has lower temperature. The thermal energy of the thermometer will 'flow' in the water and the volume shrinks, causing the liquid to go down. Simple thermodynamics.

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling

Distance covered = speed x timethe distance traveled going against the stream = distance traveled with the stream.therefore it is the speed and the time that are the variables.as he travels the same distance both ways, speed x time is the same for each way.going upstream his speed is 4 kph; going downstream his speed is 6 kph.therefore we have two simultaneous equations: time upstream x 4 = time downstream x 6time upstream + time downstream = 60 minutestherefore we have the equation: time upstream = 6/10 hour, time downstream therefore = 4/10 hour.distance traveled at 4km/hr in 6/10 hour = 24/10 = 2.4km.check: distance traveled at 6km/hr in 4/10 hour = 24/10 = 2.4km.