Let’s go through each question to verify the answers given:

13. Football kicked upward

• Given: Takes 1.9 seconds to reach the highest point.
• Total time in the air: Time up + Time down = $1.9 \times 2 = 3.8$ seconds.
• Answer: $\mathbf{3.8 \text{ s}}$ (Correct, option C).

14. Rock thrown downwards off a cliff

• Initial velocity ($v_0$): $6.0 \, \text{m/s}$ (downwards)
• Time ($t$): 3 seconds
• Using the formula: $v = v_0 + at$
  • Acceleration ($a$) is $-9.8 \, \text{m/s}^2$ (downwards).
  • Calculation: $v = 6.0 + (-9.8)(3) = 6.0 - 29.4 = -35.4 \, \text{m/s}$.
• Answer: $\mathbf{-35.4 \, \text{m/s}}$ (Correct, option B).

15. Fastest reaction time in a reaction time lab

• Given distances fallen by different people: Smaller distance indicates faster reaction time.
  • Smallest distance: Sal at $0.18 \, \text{m}$.
• Answer: $\mathbf{\text{Sal}}$ (Correct, option C).

16. Greatest jumping velocity based on maximum height

• Heights given: Higher jump height implies a greater initial jump velocity.
  • Greatest height: Bob at $0.41 \, \text{m}$.
• Answer: $\mathbf{\text{Bob}}$ (Correct, option B).

17. Acceleration of gravity on another planet

• Initial velocity ($v_0$): $0 \, \text{m/s}$
• Final velocity ($v$): $6.80 \, \text{m/s}$
• Time ($t$): $5.20 \, \text{s}$
• Using the formula: $a = \frac{v - v_0}{t} = \frac{6.80 - 0}{5.20} = 1.31 \, \text{m/s}^2$ (downwards).
• Answer: $\mathbf{-1.31 \, \text{m/s}^2}$ (Correct, option D).

Summary

The answers in the image are correct for all questions.

Would you like more detailed calculations for any of these problems?

Here are five additional related questions you might find interesting:

1. How would the answer to question 13 change if the football was kicked from a higher elevation?
2. What would be the impact of air resistance on the answers to questions 13 and 14?
3. How can we determine reaction time more precisely in question 15?
4. What is the relationship between jump height and initial velocity in question 16?
5. How would the answer to question 17 change if the alien's planet had different atmospheric conditions?

Tip: When solving motion problems, clearly label each variable (like initial velocity $v_0$, acceleration $a$, etc.) to keep track of what you know and what you're solving for.