- #1

FaroukYasser

- 62

- 3

## Homework Statement

A heater with a variable power is surrounded by ice in a funnel. The heater is turned on on 70W and the ice starts melting. once the rate of dropping of droplets is constant. The mass of water falling is then calculated for 5 minutes and it is found that 0.26 g/s falls every second. The experiment is repeated for 110W for 5 minutes also and the mass is found to be 0.38 g/s, Find:

1) The latent heat of fusion of ice in J/g

2) The heat gained from the surrounding per second

## Homework Equations

Energy supplied by heater + heat gained from surrounding = mass * latent heat of fusion or in symbols:

E + h = mL

## The Attempt at a Solution

Okay so I am having two ideas to solve this and I am not sure which one I should choose:

**Method 1:**

For the first time with 70 W.

E + h = mL

(70x1) + h = 0.26L (Equation 1)

For the second time with 110 W

(110x1) + h = 0.38L (Equation 2)

Equation 2 - Equation 1

40 = 0.12L >>>> L = 333 J/g to 3s.f

subbing in L into any equation. h = 16.7 J/s (W)

Method 2

L = E/m

using the first value once. L = 70/0.26 = 269.2

using second valiue of L = 110/0.38 = 289.5

Average is 279 J/gWhich method should I use?. does method one have any flaws and if so what are they. does Method 2 have any flaws and if so what is it?

Thanks in advance :)