The trains take <u>57.4 s</u> to pass each other.
Two trains A and B move towards each other. Let A move along the positive x axis and B along the negative x axis.
therefore,

The relative velocity of the train A with respect to B is given by,

If the train B is assumed to be at rest, the train A would appear to move towards it with a speed of 170 km/h.
The trains are a distance d = 2.71 km apart.
Since speed is the distance traveled per unit time, the time taken by the trains to cross each other is given by,

Substitute 2.71 km for d and 170 km/h for 

Express the time in seconds.

Thus, the trains cross each other in <u>57.4 s</u>.
Answer:
1) Periodically check the no stop or NDL time on their computers
2) The dive computer planning mode can be used if available
3) Make use of a dive planning app
4) Check data from the RDP table or an eRDPML
Explanation:
The no stop times information from the computer gives the no-decompression limit (NDL) time allowable which is the time duration a diver theoretically is able to stay at a given depth without a need for a decompression stop
The dive computer plan mode or a downloadable dive planning app are presently the easiest methods of dive planning
The PADI RDP are dive planners based on several years of experience which provide reliable safety limits of depth and time.
The gravitational force between two objects is given by:

where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the separation between the two objects
The distance of the telescope from the Earth's center is

, the gravitational force is

and the mass of the Earth is

, therefore we can rearrange the previous equation to find m2, the mass of the telescope:
<span>Actually in this case heat energy is being transferred. Heat
energy or thermal energy is transferred from the burning of wood to the
sausages for it to be cooked. The sausage is being heated by the fire and is
absorbing the heat or thermal energy.</span>