Question

question 10 (1 point)
a train approaches a rail yard with a velocity of 20 m/s w. after 35 s, the train has a velocity of 7.0 m/s w. what is the average acceleration of the train?
(a) 0.37m/s² w (b) 0.37 m/s² e
(c) 0.26 m/s² w (d) 0.26 m/s² e

Explanation:

Step1: Define sign convention

Let [W] be positive, so [E] is negative.
Initial velocity $v_i = 20$ m/s, final velocity $v_f = 7.0$ m/s, time $t = 35$ s.

Step2: Use acceleration formula

Average acceleration $a = \frac{v_f - v_i}{t}$

Step3: Substitute values

$a = \frac{7.0 - 20}{35} = \frac{-13}{35} \approx -0.37$ m/s²
The negative sign means direction is [E].

Answer:

(b) 0.37 m/s² [E]