Question

if velocity is positive, which would most likely yield a negative acceleration?
a final velocity that is faster than an initial velocity.
a time that is less than a half hour.
an initial velocity that is faster than a final velocity.
a time that is greater than a half hour.

Explanation:

Step1: Recall acceleration formula

Acceleration is defined as $a = \frac{v_f - v_i}{t}$, where $v_f$ = final velocity, $v_i$ = initial velocity, $t$ = time (always positive).

Step2: Analyze positive velocity condition

Given initial velocity $v_i > 0$, we need $a < 0$. Since $t>0$, the numerator $v_f - v_i$ must be negative.

Step3: Solve for velocity relationship

$v_f - v_i < 0$ rearranges to $v_i > v_f$.

Answer:

C. An initial velocity that is faster than a final velocity.