PhysicsName ___________________________________________________ Date _______

The diagram shows an aquarium which is made of glass of negligible heat capacity. It contains 20 kg of water at 25 °C.

During the night the temperature of the water falls to 20 °C.

(a) Calculate the fall in temperature of the water.

_________________________________________________________________[1]

(b)Calculate the energy lost by the water when it cools from 25 °C to 20 °C. The specific heat capacity of water is 4200 J/kg °C.

[3]

(c) A 400 W heater was used to raise the temperature of the water from 20 °C to 25 °C. For how many minutes must the heater be switched on, neglecting energy losses to the room.

[3]

2.a) What is meant by the term specific heat capacity?

_____________________________________________________________

_____________________________________________________________ [1]

b)) A can contains 170 g of water which has a specific heat capacity of 4200J/kg K. Calculate the quantity of energy required to required to heat the can If the temperature move from 19oC to 29 oC.

[3]

3.The water bath contains 3.0 kg of water and the specific heat capacity of water is 4200 J/(kg °C).a) Show that the energy needed to warm the water from 40 °C to 50 °C is 126,000 J.

[3]

b) The time taken to heat the water is 30 seconds. Show that the power of the heater is 382W. You may assume that all of the energy from the heater is used to raise the temperature of the water.

[3]

c) In every hour, the heater is on for 3 minutes. Calculate the amount of energy in kW h used by the heater in one hour.

[3]