Are there any options??
I would have to say metal of course but without options I can't assume anything
Their relative speed is the sum of 60 and 40 or 100km/hr. They will travel the 150km in 1.5 hrs. When two object approach each other, the closing speed is just the sum of the speeds, therefore, the closing speed is your case is 100kph. So they will meet in 1.5 hours.
Answer:
The possible thickness of the soap bubble = 
Explanation:
<u>Given:</u>
- Refractive index of the soap bubble,

- Wavelength of the light taken,

Let the thickness of the soap bubble be
.
It is given that the soap bubble appears very bright, it means, there is a constructive interference takes place.
For the constructive interference of light through a thin film ( soap bubble), the condition of constructive interference is given as:

where
is the order of constructive interference.
Since the soap bubble is appearing very bright, the order should be 0, as
order interference has maximum intensity.
Thus,

It is the possible thickness of the soap bubble.
Answer:
0 (there is no speed)
Explanation:
If an object is at rest, it is not moving, and it doesn't have a speed, so the speed is zero.