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.

Answer 1

An initial velocity that is faster than a final velocity.

Reason: a = (v_f − v_i)/Δt. If v_i > v_f (and Δt > 0), the numerator is negative so acceleration is negative.