Question

How long will it take a 500-w heater to raise the temperature of 400g of water from 15.0°c to 98.0c.

Answer 1

Explanation:

Hey mate,..

E=(98-15)×400×4.2

E=139440J

t=E/P

t=139440/500=278.88s

Hope it will help you

Answer 2

Given,

Mass = 400 g

Power (P) = 500 W

Temperature ($T_1$) = 15.0°c

Temperature ($T_2$) = 98.0°c.

To Find,

Time to raise the temperature

Solution,

We know the formula for energy is given by,

     E = Change in Temperature * mass * specific heat of water

Here, Change in temperature is ($T_2-T_1$) = 83°C

Substituting the given values we get,

     E = 83 × 400 × 4.2       (Water has a specific heat capacity of 4.186 J/g°C)

     E = 139440 J

Now, we know  

     $Power =\frac{Energy}{Time}$

             $P = \frac{E}{T}$

             $T = \frac{E}{P}$

Substituting the given values we get,

             $T = \frac{139440}{500}$

              $T = 278.88 sec$

Therefore, it will take 278.88 seconds to raise the required temperature.