honestly I have no clue....?

Question

A woman finds the front windshield of her car covered with ice at -12.8°C. The ice has a thickness of 4.60 10-4 m, and the windshield has an area of 1.25 m2. The density of ice is 917 kg/m3. How much heat is required to melt the ice?

this problem is listed as easy, but I'm stuck have no idea how to do it. I know you should use the formula Q=mL or change temp=Q/constant*mass<

Answer 1

You're right about using Q = mL.
First find the volume of ice, then you can find its mass.

Volume = Area * thickness (it's a rectangular solid).
Once you have this volume, multiply by density to get its mass.

First, before the ice starts melting, you must heat it to 0 degrees C. So use Q1 = mC(12.8 deg C).

The second part is melting the ice. Use Q2 = mL, using the mass you obtained above. Add Q1 and Q2. Watch your units.

Answer 2

There are two steps to solve the problem.

First figure out the volume of the ice.

Second figure out how much the temperature of the ice will need to increase to melt the ice.

1 cc of water needs 1 calorie to increase it one degree. That is the important conversion.

Answer 3

Find the mass of ice using Density/Volume=Mass
then you Q=mct Energy = mass* specific heat* cahnge in temp
don't forget to the the cahnge in phase from ice to water by its heat of fushion

Answer 4

Use

mass = density*volume.

You have the volume of the windshield (1.25*4.6*1e-4) and you can look up the density of ice at that temp.

Answer 5

all the energy she can get out of her defroster turned on high.