Year 12s: what will be the first way you research your future options? >>

M1 vectors

username2199397

https://drive.google.com/file/d/1_JMLZQA1CACt9AXu2PN3988gYal3H4-L/view?usp=drivesdk

I don't understand part b. Why didn't the solution use r=r0+vt?

Reply 1

Prasiortle

Original post by shohaib712

https://drive.google.com/file/d/1_JMLZQA1CACt9AXu2PN3988gYal3H4-L/view?usp=drivesdk

I don't understand part b. Why didn't the solution use r=r0+vt?

Because v is not constant - the particles are accelerating.

Reply 2

username2199397

Original post by Prasiortle

Because v is not constant - the particles are accelerating.

So if it was moving with a constant velocity with acceleration at 0ms^-2. Then it can be used? If it's accelerating you work out the distance covered and add it to the position vector?

Reply 3

stephen1011

First of all, Stop spamming!
Secondly, the particles are accelerating.

Reply 4

Prasiortle

Original post by shohaib712

So if it was moving with a constant velocity with acceleration at 0ms^-2. Then it can be used? If it's accelerating you work out the distance covered and add it to the position vector?

The formula r = r0 + vt requires you to know the particle's velocity, v. That can be either a constant velocity, or if the particle is accelerating, the formula is still applicable, but v now represents the average velocity. In this question, if you look at the information you've been given, you're not told the average velocity, so this formula is not applicable. You are told the initial velocity and the acceleration, so the formula r = r0 + ut + 1/2 at^2, where the bolded quantities are vectors, is applicable.