Question

Two particles travel along the space curves r(t) and u(t). A collision will occur at the point of intersection if both particles are at P at the same time. (If an answer does not exist, enter DNE. Enter your answers as a comma-separated list.)
r(t) = t^2i + (9t - 20)j + t^2k u(t) = (3t + 4)i + t^2j + (5t - 4)k point of intersection (x, y, z) =
1. Do the particles collide?
a. Yes
b. No
2. Do their paths intersect?
a. Yes
b. No

Answer 1

Answer:

Point of intersection (x, y, z) = (16, 16, 16)

1. a. Yes

2. a. Yes

Step-by-step explanation:

In order for the particles to colide (and therefore have their paths intersect), the values for the i, j, and k coordinates must be equal for a given 't':

For the i coordinate:

$i_{r(t)} =i_{u(t)}\\t^2=3t+4\\t=\frac{3\pm\sqrt{9-4*1*(-4)} }{2}\\t=4\ or\ -1$

For the j coordinate:

$j_{r(t)} =j_{u(t)}\\9t-20=t^2\\t=\frac{9\pm\sqrt{81-4*1*20} }{2}\\t=4\ or\ 5$

For the k coordinate:

$k_{r(t)} =k_{u(t)}\\t^2=5t-4\\t=\frac{5\pm\sqrt{25-4*1*4} }{2}\\t=4\ or\ 1$

As we can see, for t =4, both paths have the same coordinates and therefore they intersect and the particles will colide.

$r(4) = 4^2i + (9*4 - 20)j + 4^2k \\r(4)=16i+16j+16k\\u(4) = (3*4 + 4)i + 4^2j + (5*4 - 4)k\\u(4)=16i+16j+16k$

Point of intersection (x, y, z) = (16, 16, 16)