An 80kg quarterback jumps straight up in the air right before throwing a 0.43kg football horizontally at 15m/s . how fast will he be moving backward just after releasing the ball? (this is not the question that is to be answered)

this is the question (that needs to be answered):
which of the following best describes why you can analyze this event using conservation of momentum?

a. the throwing action is quick enough that external forces may be ignored.

b. external forces don't act on the system during the jump.

c. conservation of momentum is always the best way to analyze motion.

How many molecules are present in 3 mols of silicon dioxide (sio2)?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?