In these tasks, we are going to use equations of energy for predictions. Let's assume that, in the following, the mass of the car with all of its components and its fuel is 1000 kg.

Task 1

Let's imagine there was a car that used the heat from cooling water as its energy source. You fuel up this car with 100 [[$^\circ$]]C water that eventually cools down to 20 [[$^\circ$]]C. The mass of the water is 50 kg, and this is included in the mass of the car 1000 kg.

a. Use the thermal energy formula to find out the energy released when the body of water cools down the specified amount. Use the table for specific heat capacities (Ilmiö p. 106) to your advantage.

b. How much kinetic energy does the car receive from the body of water in this process?

c. In a perfect world, there would not be any frictions and therefore, no loss of energy. If there was no friction and if all of the thermal energy was converted to kinetic energy, find the speed of the car.

Task 2

Let's imagine there was a car that used the potential energy of falling rocks as its energy source. You fuel up this car by dropping 50 kg of stones from the height 10 m. The mass of the stones is included in the mass of the car 1000 kg.

a. Use the potential energy formula to find out the energy released when the stones fall the specified amount.

b. How much kinetic energy does the car receive from the stones in this process?

c. In a perfect world, there would not be any frictions and therefore, no loss of energy. If there was no friction and if all of the potential energy was converted to kinetic energy, find the speed of the car.