Question

A moving dot P departs from O at an initial speed of 6 m/s in the east direction and accelerates at 2 m/s2 in the east direction. 2 seconds after P's departure, dot Q departs from O to chase down P at a constant speed of k m/s in the east direction. What is the minimum speed, k, required for Q to eventually catch up to P?

Answer 1

Brilliant!

Answer 2

yeah!

Answer 3

Let me try,
s= ut+1/2 at^2
let Q eventually catch up A at distance 's'.
for A, s = 6t1 + 1/2 (2) t1^2

for 'B' the time taken to travel same distance will be t2=t1-2, right ?
so, for B,
s= k t2 = k(t1-2)

so, equating them, k (t1-2) = 6t1 +t1^2
so, k = (6t1 +t1^2)/(t1-2)
now to find minimum speed , k you can differentiate that and equate =0

Answer 4

ok thanks

Answer 5

let me know if you have further doubts/questions on this.

Answer 6

wait i'm trying

Answer 7

I got 6.

Answer 8

^ must be t1, then k=18 is min. speed.

Answer 9

OK.

Answer 10

thanks

Answer 11

yes i got 18

Answer 12

then its correct.

Answer 13

ok