Question

practice

1. when a hockey player hits a hockey puck with his stick, the velocity of

the puck changes from 8.0 m/sn to 10.0 m/ss over a time interval
of 0.050 s. what is the average acceleration of the puck?
\\(\vec{a}_{\text{avg}} = 360\\,\text{m/s}^2\\)s

1. a racehorse takes 2.70 s to accelerate from a trot to a gallop. if the

horse’s initial velocity is 3.61 m/se and it experiences an acceleration
of 2.77 m/s²e, what is the racehorse’s final velocity when it gallops?
\\(\vec{v}_f = 11.1\\,\text{m/s}\\)e

Explanation:

Step1: Recall average acceleration formula

Average acceleration $\vec{a}_{\text{avg}} = \frac{\Delta \vec{v}}{\Delta t} = \frac{\vec{v}_f - \vec{v}_i}{\Delta t}$
Define [S] as positive, so $\vec{v}_i = -8.0$ m/s, $\vec{v}_f = 10.0$ m/s, $\Delta t = 0.050$ s.

Step2: Calculate velocity change

$\Delta \vec{v} = 10.0 - (-8.0) = 18.0$ m/s [S]

Step3: Compute average acceleration

$\vec{a}_{\text{avg}} = \frac{18.0}{0.050} = 360$ m/s² [S]

Step1: Recall final velocity formula

$\vec{v}_f = \vec{v}_i + \vec{a}t$
$\vec{v}_i = 3.61$ m/s[E], $\vec{a} = 2.77$ m/s²[E], $t = 2.70$ s.

Step2: Calculate acceleration contribution

$\vec{a}t = 2.77 \times 2.70 = 7.479$ m/s[E]

Step3: Compute final velocity

$\vec{v}_f = 3.61 + 7.479 = 11.089 \approx 11.1$ m/s[E]

Answer:

360 m/s²[S]