It was one of these rainy days that we always get in the summer half-term. Our bike ride had just been cancelled due to the bad weather. Disappointed we started talking about alternative plans. Unsurprisingly, one thing led to another and we ended up talking about space travel. My daughter would not like to go to Jupiter because it is made of gas, and how could we live there? My son said that he would quite like to live on the Moon, because he “would be jumping all day long and that would be fun, wouldn’t it be mum?”
It was that comment that sparked a lively discussion about gravity and what it does to us.
Earth’s gravity is the force that holds us to the planet. Without it we would fly off. Gravity depends on the mass. Because the Earth is more massive than the Moon, Earth’s gravity is bigger than the Moon’s so the pull is stronger for any object on our planet than it would be on the Moon. For instance, if you can jump 20 cm on Earth, you could jump nearly 2 m on the Moon. Wouldn’t that be fun?
But how does gravity affect us?
Here is a nice little experiment to help us investigate.
Gravity is pulling us down, as a result we are slightly shorter in the evening than in the morning when we have spent the whole night lying in the bed.
Method of exploring the question
Measure height just before we go to bed and just after we get up.
Child 1 – 9 years old
Child 2 – 6 years old
The children designed a table to record the measurements. They had to think about what the question is what the best way is to sort out the data.
Hurray!!! We have shown that indeed gravity makes us shorter. We would be probably a little bit taller if we were living on the Moon. We used a simple measuring tape, hence the measurements are not accurate, but fluctuate a couple of centimetres. However there is a clear trend, which shows that the children are slightly taller by 2 – 3 cm in the morning.