Run and Gain Weight????

If you run really fast, you gain weight. Not permanently, or it would make a mockery of diet and exercise plans, but momentarily, and only a tiny amount.

Light speed is the speed limit of the universe. So if something is travelling close to the speed of light, and you give it a push, it can’t go very much faster. But you’ve given it extra energy, and that energy has to go somewhere.

Where it goes is mass. According to relativity, mass and energy are equivalent. So the more energy you put in, the greater the mass becomes. This is negligible at human speeds – Usain Bolt is not noticeably heavier when running than when still – but once you reach an appreciable fraction of the speed of light, your mass starts to increase rapidly.

Would a Strawberry Sun be Hot like our sun?

Why is the sun hot?  Why does it stay hot?  What if...the sun was made of strawberries?  Would it be hot?
The answer is well...yes and no.  The sun is hot because of its weight...billion billion billion tons creating vast gravity which pulls its core under colossal pressure.  This pressure leads to enormous temperature.  So if you took a billion billion billion tons of strawberries and stuck them in space it would create equal pressure and a just as high a temperature.  That is the yes part....

Strawberry Sun

Now for the NO part:  Even though the heat would be similar to the sun because strawberries are not made of hydrogen the fusion reaction that keeps the sun going wouldn't get under way and our strawberry sun would cool from its initial heat rather than burning for billions of years!