Question

Two particles A and B start at O and travel in opposite direction along the circular path at constant speed `V_a = 0.7m/s` and `V_b = 1.5m/s` respectively. Determine the time when they collide(radius = 5m)?

Answer 1

They collide after about 10 s.

Explanation:

The circumference of the circle is `2*pi*r = 31.42 m`. Let the distance traveled by them be `d_A and d_B` respectively. So we know that

`d_A + d_B = 31.42 m`

Let the time between start and collision be t. Then we know that

`d_A = 0.7 m/s * t and d_B = 1.5 m/s *t`

Substituting into the first equation

`0.7 m/s * t + 1.5 m/s *t = 31.42 m`

`t = (31.42 m)/(0.7 m/s + 1.5 m/s)`

`t = (31.42 cancel(m))/(2.2 cancel(m)/s) = 14.28 s`

So, rounding that to 1 significant digit (because radius is 5 m), they collide after about 10 s.

I hope this helps,
Steve