Final answer:
The acceleration of the boy on the bicycle, as he goes up the hill, can be calculated using the change in velocity and time, resulting in an acceleration of -0.267 m/s², which indicates deceleration.
Step-by-step explanation:
The student's question involves calculating the acceleration of a boy on a bicycle as he ascends a hill. Given that the boy's initial velocity is 12 m/s and his velocity at the top of the hill is 8 m/s over a time span of 15 seconds, we can find the acceleration using the formula a = (v_f - v_i) / t, where a is acceleration, v_f is the final velocity, and v_i is the initial velocity.
To solve for acceleration: a = (8 m/s - 12 m/s) / 15 s = -4 m/s² / 15 s = -0.267 m/s². The negative sign indicates that the bicycle is decelerating as it goes up the hill (i.e., a reduction in speed).