Im so bored need someone to talk to :)

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

A100 kg running back runs at 5m/s into a stationary linebacker. it takes 0.5 for the running back to be completely stopped

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron