help needed: 9702_s07_qp02

[XPFMember]

Assalamoalaikum!!

can sumeone tell me how to do Q:2 (d) of http://www.xtremepapers.net/CIE/International A And AS Level/9702 - Physics/9702_s07_qp_2.pdf

dont understand y are we ignoring ut in the eqn s=ut + 1/2 a t^2

 

[Tweety-Angie]

It is because the electron is initially at rest.
Initial velocity u = 0
So, ut = 0

 

[XPFMember]

but it doesnt mention it :?

 

[hassam]

its a projectile motion type scenario....we r using 2nd equation for vertical motion......and initially vertical component of velocity was zero

 

[XPFMember]

ohhhhh right!!! Jazak Allah

 

[Tweety-Angie]

Ooooo! got it now! thanks!!