AP Physics 1 Question 56: Answer and Explanation

Question: 56

6. A bubble in a glass of water releases from rest at the bottom of the glass and rises at acceleration a to the surface in t seconds. How much farther does the bubble travel in its last second than in its first second?

• A. at
• B. (t - 1)a
• C. (t + 1)a
• D. at

Correct Answer: B

Explanation:

B The distance travelled in the first second can be found using the Big Five,

d_first = v₀t_first +

Using t_first = 1 s and v₀ = 0 m/s since the bubble starts at rest, the equation becomes

The distance traveled in the last second can be found using another Big Five equation.

Using t_last = 1 s and v_final = v₀ + at_total = at_total, the equation becomes

d_last = at_total – a

The question is asking for the difference in the distance, so

d_last – d_first = at_total – a – a = at_total – a = (t – 1)a