a x
5
M/s.
18
2. M/s to km/hr conversion: a m/s =
a x
18
Km/hr.
5
3. Formulas for finding Speed, Time and Distance Speed, Time and Distance:
Speed =
Distance
,
Time =
Distance
,
Distance = (Speed x Time).
Time
Speed
km/hr to m/sec conversion: x km/hr =
x x
5
m/sec.
18
m/sec to km/hr conversion: x m/sec =
x x
18
km/hr.
5
If the ratio of the speeds of A and B is a : b, then the ratio of the the times taken by then to cover the same distance is
1
:
1
or b : a.
a
b
Suppose a man covers a certain distance at x km/hr and an equal distance at y km/hr. Then, the average speed during the whole journey is
2xy
km/hr.
x + y
4.
5. Time taken by a train of length l metres to pass a pole or standing man or a signal post is equal to the time taken by the train to cover l metres.
6. Time taken by a train of length l metres to pass a stationery object of length b metres is the time taken by the train to cover (l + b) metres.
7. Suppose two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u - v) m/s.
8. Suppose two trains or two objects bodies are moving in opposite directions at u m/s and v m/s, then their relative speed is = (u + v) m/s.
9. If two trains of length a metres and b metres are moving in opposite directions at u m/s and v m/s, then:
The time taken by the trains to cross each other =
(a + b) sec. (u + v)
10. If two trains of length a metres and b metres are moving in the same direction at u m/s and v m/s, then:
The time taken by the faster train to cross the slower train =
(a + b) sec. (u - v)
11. If two trains (or bodies) start at the same time from points A and B towards each other and after crossing they take a and b sec in reaching B and A respectively, then: