What is the average acceleration of a jet ski that goes from rest to 10 m/s west in 4 s? Take the direction west to be positive, and east to be negative.

A.
2.5 m/s2

B.
-2.5 m/s2

C.
0.4 m/s2

D.
-0.4 m/s2

Question

What is the average acceleration of a jet ski that goes from rest to 10 m/s west in 4 s? Take the direction west to be positive, and east to be negative.	
 
 A.
2.5 m/s2
 
 B.
-2.5 m/s2
 
 C.
0.4 m/s2
 
 D.
-0.4 m/s2

jhannybean · Answer

$$a_{avg} =\frac{\Delta v}{\Delta t}$$

jhannybean · Answer

that means if it starts at rest, $v_i = 0 \ m/s$ while $v_f= 10 \ m/s$ and the change in time is when $t_i = 0 \ sec$ and $t_f= 4\ sec$

jhannybean · Answer

$$a_{avg} = \frac{\Delta v}{\Delta t} = \frac{v_f - v_i}{t_f -t_i} = \frac{10 \ m/s - 0 \ m/s}{4 \ sec - 0 \ sec}$$