Forms of energy and energy transformations

State what form of energy each of these things has:

1. a) A kite flying high at the beach.
2. b) Water stored in a reservoir, at the top of the dam.
3. c) A new, unused battery.
4. d) The flame of a camping stove.

Match each form of energy to its example and write out the four complete pairs:

1. a) Nuclear energy.
2. b) Wind energy.
3. c) Sound energy.
4. d) Electrical energy.

Examples: the doorbell, a windmill, the wall socket and the Sun.

Yasmin has a sandwich for breakfast and then plays a handball match, in which she runs and sweats a lot.

1. a) What form of energy was stored in the breakfast food?
2. b) Name two forms of energy into which her body transforms it during the match.

Vera has left her book on the top shelf of the bookcase, as shown in the figure.

1. a) What form of energy does the book have because it is so high up?
2. b) If the book falls, into what form of energy is that energy transformed while it falls?

At the neighbourhood party they have connected some large speakers, like the one in the figure.

1. a) What form of energy enters the speaker through the cable?
2. b) What form of energy comes out of it and makes us dance?

In Daniela's garden there is a solar street light that turns on automatically at night.

1. a) What form of energy does it collect from the Sun during the day?
2. b) In what form is that energy stored in the light's battery?
3. c) Write the chain of transformations that energy undergoes at night, from the battery to the light.

Iker goes down a long hill on his bike without pedalling, and brakes when he reaches the bottom, as shown in the figure.

1. a) What energy transformation takes place while he goes down and gains speed?
2. b) When braking to a stop, into what form of energy is the kinetic energy transformed?

Aitana swings on a swing higher and higher. The figure shows the swing at the highest point (A) and at the lowest point (B).

1. a) What form of energy does she have at the highest point, where she stops for a moment?
2. b) And what form of energy does she have when passing through the lowest point?
3. c) If nobody pushes her, she goes less high each time. What "thief" takes away part of the energy and into what form does it convert it?

A friend tells you: "It doesn't matter if you leave the light on, because energy is not destroyed, it is only transformed."

1. a) Is it true that energy is not destroyed?
2. b) Explain why, even so, this reasoning is wrong: think about what form of energy the bulb's energy ends up as and whether it can be reused.
3. c) Add another argument related to energy sources or money.

An electric heater of $2\ \text{kW}$ is switched on for $3\ \text{h}$. How much energy does it consume? Express it in $\text{kWh}$.

A washing machine of $2\ \text{kW}$ does a wash cycle that lasts $1,5\ \text{h}$.

1. a) How much energy does it consume, in $\text{kWh}$?
2. b) If a kilowatt-hour costs $0,20\ \text{€/kWh}$, how much does that wash cycle cost?

The microwave oven at home consumed $7,2\cdot10^{6}\ \text{J}$ in one month. Knowing that $1\ \text{kWh} = 3,6\cdot10^{6}\ \text{J}$:

1. a) How many $\text{kWh}$ has it consumed?
2. b) How much did that month of microwave use cost, at $0,20\ \text{€/kWh}$?