# Thermal Energy Graph Question

• physicsstudent111

#### physicsstudent111

Homework Statement
A 0.25 kg piece of ice is warmed by an electric heater and the following graph of temperature is produced. Assume that there has been no loss of energy to the surroundings
a) How much additional time after 150s will be required to melt all the ice
Relevant Equations
Q=mct
Q=mct+mLf

Im not really sure how to answer this question. Would you have any ideas?

The electric heater is giving off energy to the water.
What can you say regarding the power of the heater? Look at the graph

... what does it take to melt ice?

robphy and malawi_glenn
In the graph we can say the heater warms the water 10 degrees every 75s and to melt ice we need to reach a temperature of 0 degrees

In the graph we can say the heater warms the water 10 degrees every 75s and to melt ice we need to reach a temperature of 0 degrees
Does the ice automatically melt at 0 degrees?

Or, does water freeze into ice at 0 degrees?

malawi_glenn
Yes but you need to think in terms of energy. It is not enough to heat ice to 0deg to make it melt.
I gave you a hint earlier regarding the power of the heater

I think the melting point for water is 0 degrees. But I am not really sure what to say about the energy. Does there have to be more energy to fully melt the ice?

I think the melting point for water is 0 degrees. But I am not really sure what to say about the energy. Does there have to be more energy to fully melt the ice?
Yes, look it up online. Ice is hard to melt. Think about its use to keep a drink cold.

malawi_glenn
I think the melting point for water is 0 degrees. But I am not really sure what to say about the energy. Does there have to be more energy to fully melt the ice?
You wrote the formulas here, also you recently did problem with turning 100 deg water into steam. Similar logic applies to when you go from solid to liquid

PeroK