Variable Acceleration 3 • Further problems • Mech1 Ex11C • 🚀

Edexcel Applied Year 1 - Mechanics

Tues 28/1/20

[animetheascension]

Hi sir, In question 4 at the end of this video can you instead say that when the particle is at rest v=0 then you work out the discriminate of the equation for the velocity which is square root of -31. As you can't square root a negative number there are no real solutions therefore the velocity is never zero meaning the particle never comes to rest.

[revcs]

for the 1st question at 3:50 why do we have to do double derivative? the velocity is the gradient right, so would we not just derivite it and set it equal to 0 to find the values for that point where the gradient is 0?

[ELS-egho]

3:53 why do we differentitate twice instead of once? and isn't velocity and acceleration always zero at maximum and minimum velocity?

[zektric]

Hi Sir,
At 5:25, if they said for part a, for example: "Find the time that P comes to rest" would we just sub in 0 into v and then find the times, or do we differentiate to find acceleration, then sub in 0 as acceleration to then find the times?
Thanks

[elitebeast]

At 5:38 they give us the equation for velocity and when your trying to find acceleration do you only differentiate once, and only differentiate twice when ur given displacement and trying to work out acceleration from there ?

[s]

can you say for the reason why the particle in the last question never comes to rest because it has no real solutions so v is always >0

[malanhemal]

Sir, for the last question I said, it will never stop because there aren't any real roots meaning v will never be equal to zero, so there is no stopping and I drew the graph. Will I get the marks sir? I wrote the minimum points in the graph also.

[rubiksworld]

Sir how would you answer the first one because the minimum point is -1.875 but that’s not the velocity with the lowest magnitude (min velocity)?

[AzraKahraman]

Hi Sir, at 2:50, why do we have to differentiate v, can we not just look at the sketch of the graph and see that the velocity is greatest at t=0 when v=20

[favourolamidesodimu]

For the first question in this video what if when we subed in a value for the turning point and we got a really negative number like -25 will the maximum speed still be 20 ???

[teacupcakes]

5:36 but what if t=0.5, its still a positive number :/

[quervy]

Sir, where are the answers to the questions?