How to measure how long Fidget Spinner rotates without a clock
Why? Because obviously the watch is not available but the laser device and light sensor are sold in the market.Professor American explains the technique of climbing walls with bamboo pole of Vietnamese task force
Using only a long bamboo stick, the Vietnamese task forces can climb walls quickly and perpendicular to the wall surface, which seems impossible.What happens if everyone on Earth dances for a while?
Earth has about 7 billion people with a total weight of 363 billion kg. When all people on earth gather and dance together for a while, it creates a small force. So can this