"what is the mass in kg of a 3920n piano? " which formula would this question use? f=ma or w=mg?

Alead ball is dropped into a lake from a diving board 5m above the water . it hits the water with a certain velocity and then sink with constant velocity in bottom . it reaches the bottom 5 second after it is dropped if g= 10m/s2 . find depth of the lake and average velocity of the ball ?

Your town is considering building a biodiesel power plant describe at least two advantages and two disadvantages

In an experiment, how can i change human errors? be specific.