A 0.057 kg tennis ball and a tennis racket collide. The racket has an initial momentum of -2.80 kg•m/s and a final momentum of -1.97 kg•m/s. The ball has an initial momentum of 0.02565 kg•m/s. If you assume the collision is elastic, what is the final velocity of the ball? A. -4.75 m/s
B. -83.27 m/s
C. -0.80 m/s
D. -14.11 m/s
(The picture is my notes that I don't understand) :/ Please help

Explain vector addition, triangle method and parallelogram method

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.

If you wanted to move an electron from the positive to the negative terminal of the battery, how much work w would you need to do on the electron? enter your answer numerically in joules.