You have to understand some basic
concepts before we start to solve problems on Time and Distance.
*Speed Definition: The time covered
per unit time is called as speed.
Basic formula: Speed = (Distance/Time)
Manipulation of
formula: Time = (Distance/Speed)
Distance
= (Speed * Time)
*Unit Conversion: If you want to convert speed from
KMPH (Kilometres Per Hour) into m/s (metres per second) follow
some basic tricks.
1KMPH = (1*1000)/(60*60) metres/seconds
=(1000/3600)
m/s
=10/36 m/s
=5/18
m/s
so 1 KMPH is 5/18 m/s.
so 1 KMPH is 5/18 m/s.
Problem I] if you wants to convert speed from KMPH to m/s, multiply that number with (5/18)
i.e. 54 KMPH speed can be
converted into m/s as (54)*(5/18)
=3*5 (as
18 cancel 54)
=15
m/s
Problem II] if you want to convert speed
from m/s to KMPH, multiply that number with (18/5)
i.e. 25 m/s speed can be converted
into KMPH as 25*(18/5)
=5*18 (as
5 cancel 25)
=90KMPH
*Average Speed = (Total distance
traveled/ Total time taken)
Consider a bus traveling from A to
B of distance d with the constant speed p and same bus travel back from B to A
of same distance d with different constant speed q.
As per the speed formula Time
= (Distance/Speed)
So Total
time taken = (Time while going)+(Time while coming back)
=(d/p)+(d/q)
=d{(p+q)/(pq)}
Total
distance traveled:(d+d)=2d
By the formula
Average
Speed = (Total distance traveled/ Total timer taken)
Average
Speed =
(2d/d{(p+q)/(pq)})
Average
Speed = 2pq/(p+q)
*If a bus covers part of there
journey at a constant speed p and remaining part of journey at
a different constant speed q, and the distance traveled of the two
part is in the ratio as m:n, then the Average Speed for
entire journey is given as below
Average
Speed = {(m+n)*(pq)}/(mq+np)
Previously asked in Bank
Examinations, most important and Solved questions on Time and Distance
1] Express 72 KMPH in metres/second?
Sol: 72
KMPH
=
72*(5/18)
=
4*5 m/s
=20
m/s
2] Express 35 m/s in KMPH?
Sol: 35
m/s
=35*(18/5)
=7*18
=126
KMPH
3] A car can travel 350KM in 4 hours.
If its speed is decreased by 12.5 KMPH, How much time does the can takes to
caver a distance of 450KM?
Sol: Speed of
the car
Speed =
(Distance/Time)
Speed =(350/4)
Speed
=87.5 KMPH
Now speed of the is
reduced by 12.5
So new speed of the becomes
(87.5-12.5) = 75 KMPH
If car travels with new speed of
75 KMPH, the time taken to cover distance of 450 is given by
Time = (Distance/ Speed)
Time = (450/75)
Time = 6 Hours
So if car travels with speed 75
KMPH, 6 hours will be required to cover 450 KM of distance.
4] A bus can travel a certain
distance travelling at a speed 60 KMPH and return with the speed 40 KMPH to the
starting point. Find the average speed for entire journey?
Sol: Average
Speed = (Total distance traveled/ Total timer taken)
Average
Speed = 2pq/(p+q)
Here
no distance is mentioned, so do not about distance, only place the values of p
and q
Where
p is speed while going
And q
is speed while coming back to the original point.
So,
Average
Speed = (2*60*40)/(60+40)
=(4800)/100
=48
KMPH
Average
Speed of the bus is 48 KMPH
5] A boy wins 200m race in 24
seconds, then his speed is?
Sol: Speed
= (Distance/Time)
Speed = (200/24)
Speed
= 30 m/s
Speed of the is 30 metres per
second.
6] If a train cover distance of
350km in one hour, What is the speed of the train in m/s?
Sol: Speed = (Distance/Time)
Speed = (350km/1hr)
Speed = 350 KMPH
To convert
this speed from KMPH to m/s multiply it with 5/18
Speed in m/s = 350*(5/18)
= 97.22 m/s
7] A bus can travel a certain
distance travelling at average speed 48 KMPH and it takes 3 hour to come back
at starting point. Find the distance covered
by bus in one side?
Sol: Let total distance covered by bus be x;
one
side distance covered by bus = x/2;
Average Speed = (Total distance
traveled/ Total timer taken)
48 = x/3;
X=144
Here,
total distance covered by bus is 144 KM;
so,
one
side distance covered by bus = x/2;
=144/2
one side distance covered by bus is 72 KM.
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