A proton initially moves left to right long the x‑axis at a speed of 2 ´ 103 m/s. It moves into an electric field, which points in the negative x direction, and travels a distance of 0.2 m before coming to rest. What acceleration magnitude does the proton experience?

Question

A proton initially moves left to right long the x‑axis at a speed of 2 ´ 103 m/s. It moves into an electric field, which points in the negative x direction, and travels a distance of 0.2 m before coming to rest. What acceleration magnitude does the proton experience?
 
a. 6.67 ´ 103 m/s2
b. 1.0 ´ 107 m/s2
c. 9.33 ´ 109 m/s2
d. 2.67 ´ 1011m/s2
 
Please show all calculations THANKS!

bobpursley · Answer

Vf^2=Vi^2+2ad you know Vf=0, Vi=2E3m/s, d=.2m solve for a

jolanta · Answer

why is the 'a'---the variable i'm solving for positive though? I got a (-) 'a' when I followed your steps....thanks for the help though!

bobpursley · Answer

Of course, a is negative, it is deaccelerating in the +x direction, or accelerating in the -x direction.