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2J9HJCG Smiling woman wearing towel spraying deodorant on body at home

This week鈥檚 new questions

Why do aerosol cans suddenly turn cold when they run out? And why does a round coin rolling down a hill stay upright, whereas a 鈥渟quare鈥� coin sliding down a slope soon falls over?

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Someone throwing rubbish in bin. rubbish bin. Trash.

Is it more sustainable to flush a tissue or put it in the bin?

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2DHCKHY High angle view of smiling boy with gap toothed in park

Why is teething so painful for babies but not growth of second teeth?

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experienced hand of the old music teacher helps the child pupil; Shutterstock ID 379622230; purchase_order: -; job: -; client: -; other: -

Why is the left hand used for intricate violin fingerwork? (Part 3)

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Four cheerful female friends having fun on summer road trip

This week鈥檚 new questions

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iss067e189024 (July 16, 2022) --- The sun's rays begin to illuminate the Earth's atmosphere as the International Space Station flew into an orbital sunrise 261 miles above Texas. iss067e189024 NASA ID: iss067e189024 iss067e189024 (July 16, 2022) --- The sun's rays begin to illuminate the Earth's atmosphere as the International Space Station flew into an orbital sunrise 261 miles above Texas. Date Created:2022-07-16 Center:JSC

When was the first sunrise on Earth?

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Bengal cat washing itself on bed; Shutterstock ID 1123136123; purchase_order: -; job: -; client: -; other: -

Why do cats wash themselves, while dogs don鈥檛?

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MNN37P Illustration comparing the planets of the Solar System and the Sun on the same scale. The planets are shown to scale relative to each other but their distances are not. From left to right the bodies are: the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Will the planets of our solar system ever line up in a row? (Part 2)

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Big dog meets small dog; Shutterstock ID 2045462630; purchase_order: -; job: -; client: -; other: -

This week鈥檚 new questions

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HCNBCF THOR: THE DARK WORLD, Chris Hemsworth as Thor, 2013. ph: Jay Maidment/?Walt Disney Studios/courtesy Everett Collection

Could you make a machine that 鈥渇lew鈥� like Thor鈥檚 hammer in the comics?

Such machines already exist, in a sense, say our readers - but an immortal being might also be using effects science has yet to understand

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If humans colonised Mars, how would they calculate time? (Part 2)

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This week鈥檚 new questions

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If a cyclist and runner exercise together, who expends more energy?

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Why do I need to be able to pronounce a word to recall it?

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