Question

a bus slams on its breaks and goes from 38 km/hr to 23 km/hr in 3 seconds. what is its acceleration? answer: what are the units for your answer? select one: ○ kilometers ○ seconds ○ km/hr ○ km/hr/s ○ hours

Explanation:

First Sub - Question (Acceleration Calculation)

Step1: Recall acceleration formula

Acceleration \(a=\frac{\Delta v}{\Delta t}\), where \(\Delta v = v_f - v_i\) and \(\Delta t\) is the time interval. Here, \(v_i = 38\space km/hr\), \(v_f=23\space km/hr\), \(\Delta t = 3\space s\).

Step2: Calculate change in velocity

\(\Delta v=23 - 38=- 15\space km/hr\)

Step3: Calculate acceleration

\(a=\frac{- 15\space km/hr}{3\space s}=- 5\space km/hr/s\) (The negative sign indicates deceleration)

Acceleration is change in velocity per unit time. Velocity unit here is \(km/hr\) and time unit is seconds (\(s\)), so units of acceleration are \(km/hr/s\).

Answer:

\(-5\space km/hr/s\) (or \(5\space km/hr/s\) if magnitude is considered)

Second Sub - Question (Units of Acceleration)