What is linear momentum and its conservation? What is mechanical energy?Full info

What is physics ? What is mechanics?Who was Sir Issac Newton and their inventions.Full info in breif

What is prehistory?What do BC and AD mean?Full info

Water/Its formation and its importance/Interesting facts

What are tropics and equators/What causes Season/ Full info in English

Human Heart/Full info in English

What is a star / Full info in English

HOMO HABILIS /full info in english