In which of the following situations is work not being done?
A) Susanna lifts a letter to read it, using a force of 0.2 N.
B) A weightlifter holds a weight above his head using a force of 200 N.
C)A small bulldozer pushes a pile of dirt across the ground with a force
of 150 N
D)Johnny lifts a textbook from the floor to the top of his desk using a
force of 3 N.

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.