A ball is thrown up with 20m/s at an angle of 60 with x-axis, the velocity of the ball at the top position is?

Critical mass is the of material required to produce a chain reaction. a.) minimum amount b.) atomic mass c.) precise amount d.) maximum amount

Matter that emits no light at any wavelength is called

Ineed to answer this problem but i lack in knowledge, what should i study to answer this problem? i have never used derivatives in a physics problem so i'm not sure what's happening and i can't find videos explaining.