Mechanic question help (1 Viewer)

[king.rafa]

hey this is from the cambridge 4 unit book
A particle moves in a straight line away from a fixed point O in the line, such that when its distance from O is x its speed v is given by v=k/x, for some constant k.
a) show that the particle has a retardation which is inversely proprtional to x^3.
b) if A, B, C, D are points in that order on the straight line, such that AB, BC, and CD are all equal show that the times takken to travel these sucessive distances increase in arithemtic progression.

Im having problem with part b. I give the solution i got to (a) if it helps ne1 willing to help on part b.
v=k/x
a=v dv/dx = k/x (-k/x^2)= -k^2/x^3

 

[ssglain]

Here you go.

Which school do you attend? It seems rather early to be cracking at Mechanics.

 

[SoulSearcher]

It's quite possible he's going ahead and doing work that hasn't been covered so far at his school.

 

[ssglain]

Just a correction:
To formally show that the sequence is an AP you need to show that T2 - T1 = T3 - T2 = the common difference.

My bad.

 

[kony]

It's quite possible he's going ahead and doing work that hasn't been covered so far at his school.

i think ssglain would know, given her nothing less than absurdly good results.