Speed, distance, time. Rather than trying to do fractions in your head, you'll find it a lot easier to think in miles per minute rather than miles per hour. You'll also discover that the numbers in the questions are chosen so you can do it this way.
e.g. Aircraft flying at 420 knots. How far in 4 minutes?
420 knots = 7 nautical miles per minute. Distance travelled = 4 x 7 = 28 nautical miles. For me, that's easier than 420 x (1/15)...
So where does 420 knots = 7nm per minute if not a fraction in your head?
Theres obviously more than one way to skin a cat.
I was pointing out a way to save time that works for me. Also it would be as simple as 420 x (4/60) which is same as writing (420 x 4)/60 which boils down. One calculation
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Hey-Hoh, more than one way to do it.
BTW, i dont remember any question in Knots and Nautical Miles, it was all mph and miles as i remember. But you will NOT need to convert any units.
Also for collision times that are for objects at same speed, half the distance.
For collisions where they are at different speeds add the speeds up.
1 plane at 500mph another at 400mph, 30 miles apart. How long before they collide.
Add their speeds together to make 900mph.
t= 30/900
simplify...
= 3/90hr
and again..
= 1/30 of an hour
= 2mins
You can bang through them in seconds if you are comfortable with fractions, but again its what YOU are comfortable with.
Good luck