Question 9: the correct answer is True. Did you get it right? Score 1 point.
Question 10 of 10
Water always boils at 100 °C, anywhere.
Why, in question 9: The Eiffel Tower is taller in summer.
It's true. Iron expands when heated, and on hot days the Eiffel Tower can be about 15 centimeters taller than in winter. The top also leans slightly away from the side heated by the sun.
Metal that grows and shrinks
Almost every material increases in size when heated, because its particles move more and drift further apart. In large structures, the difference becomes visible.
That is why bridges and train tracks have expansion joints, small gaps that let the metal grow without bending the structure.
The Eiffel Tower was built for the 1889 Universal Exhibition in Paris and was supposed to last only 20 years. It was kept, among other reasons, because it came to be used for radio broadcasts.
The tower is over 300 meters tall, counting the antennas at the top, and is repainted roughly every seven years to protect the iron from rust.
When it opened, the tower was the tallest structure ever built by humans, a title it held until 1930, when it was surpassed by the Chrysler Building in New York.
