1 m/s =18/5 km/h,
If a man travels different distances d1,d2,d3,
....... and so on in different time t1,t2,t3 respectively then,
Average speed
=total travelled distance/total time taken in travelling distance
=d1+d2+d3/ t1+t2+t3
Q2 If a man travels different distances d1,d2,d3,
and so on with different speeds s1,s2,s3, respectively then,
Average speed = d1+d2+d3/(d1/s1)+(d2/s2)+(d3/s3)
If a distance is divided into n equal parts
each travelled with different speeds, then, Average speed
If d1 distance is travelled in t1 time and d2
distance is travelled in t2 time then,
d1t2=d2t1
If an object increases/decreases its speed
from x km/hr to y km/hr. to cover a distance in t2 hours in
place of t1 hours then [Here (t2 – t1) will be given].
Distance = [xy/ x-y] X (t2 – t1)
If an object travels certain distance with the speed of
A / B of its original speed and reaches its destination
‘t’ hours before or after, then the taken time by object
travelling at original speed is
If a man travels at the speed of s1, he
reaches his destination t1 late while he reaches t2 before
when he travels at s2 speed, then the distance between the
two places is D =
[ (s1 x s2) / (s2-s1) ] x (t1+ t2)
Time taken by 1st man to reach B after meeting 2nd
man at C is ‘t1’ and time taken by 2nd man to reach A after
meeting 1st man at C is ‘t2’ then:
=>Speed of 1st man s1 / Speed of 2nd man s2=√(t2/t1)
=>Distance from A to B = s1t1 + s2t2
If both objects run in opposite direction
then, Relative speed = Sum of speeds.
If both objects run in the same direction then,
Relative speed = Difference of Speeds.
Time taken in meeting = Distance between them / RelativeSpeed
Let a man take ‘t’ hours to travel ‘x’ km. If
he travels some distance on foot with the speed u km/h
and remaining distance by cycle with the speed v km/h,
then time taken to travel on foot.
Time =(vt-x ) / (v-u )
Distance travelled on foot = Time × u
Q- If any one overtakes or follows another,
then time taken to catch or meet
=distance between them / Relative speed
or meet = (Speed of 1st traveller time ) / (Differenc of speeds)
Total travelled distance to catch the thief
= (Product of speeds) x time / (Difference of speeds)
If a man covers 1/x part of Journey at u km/h, 1/y part at v km/h and
1/ z part at w km/hr and so
on, then his average speed for the whole journey will be
1 / [(1/xu)+ (1/yv) + ( 1/ zw) ]
If a man travels different distances d1,d2,d3,
....... and so on in different time t1,t2,t3 respectively then,
Average speed
=total travelled distance/total time taken in travelling distance
=d1+d2+d3/ t1+t2+t3
Q2 If a man travels different distances d1,d2,d3,
and so on with different speeds s1,s2,s3, respectively then,
Average speed = d1+d2+d3/(d1/s1)+(d2/s2)+(d3/s3)
If a distance is divided into n equal parts
each travelled with different speeds, then, Average speed
If d1 distance is travelled in t1 time and d2
distance is travelled in t2 time then,
d1t2=d2t1
If an object increases/decreases its speed
from x km/hr to y km/hr. to cover a distance in t2 hours in
place of t1 hours then [Here (t2 – t1) will be given].
Distance = [xy/ x-y] X (t2 – t1)
If an object travels certain distance with the speed of
A / B of its original speed and reaches its destination
‘t’ hours before or after, then the taken time by object
travelling at original speed is
If a man travels at the speed of s1, he
reaches his destination t1 late while he reaches t2 before
when he travels at s2 speed, then the distance between the
two places is D =
[ (s1 x s2) / (s2-s1) ] x (t1+ t2)
Time taken by 1st man to reach B after meeting 2nd
man at C is ‘t1’ and time taken by 2nd man to reach A after
meeting 1st man at C is ‘t2’ then:
=>Speed of 1st man s1 / Speed of 2nd man s2=√(t2/t1)
=>Distance from A to B = s1t1 + s2t2
If both objects run in opposite direction
then, Relative speed = Sum of speeds.
If both objects run in the same direction then,
Relative speed = Difference of Speeds.
Time taken in meeting = Distance between them / RelativeSpeed
Let a man take ‘t’ hours to travel ‘x’ km. If
he travels some distance on foot with the speed u km/h
and remaining distance by cycle with the speed v km/h,
then time taken to travel on foot.
Time =(vt-x ) / (v-u )
Distance travelled on foot = Time × u
Q- If any one overtakes or follows another,
then time taken to catch or meet
=distance between them / Relative speed
or meet = (Speed of 1st traveller time ) / (Differenc of speeds)
Total travelled distance to catch the thief
= (Product of speeds) x time / (Difference of speeds)
If a man covers 1/x part of Journey at u km/h, 1/y part at v km/h and
1/ z part at w km/hr and so
on, then his average speed for the whole journey will be
1 / [(1/xu)+ (1/yv) + ( 1/ zw) ]
