When an acrobat reaches the equilibrium position, the net force acting along the direction of motion is zero. why does the acrobat swing past the equilibrium position

What are the three ways that an object can accelerate

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 ?

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