A motorboat covers the distance between two spots on the river in t1=8h and t2=12h downstream and upstream respectively.What is the time required for the boat to cover this distance in still water?
Answers
Answer:
T1 = 8 h
T2 = 12 h
Let time requited in still water be t h.
Let Speed of boat be v1 and speed of stream be v2.
For downstream, d = ( v1 + v2) T1
For upstream, d = ( v1 - v2) T2
For still water, d = v1. t
Solve all three equations,
t = 2 T1 T2 / ( T1 + T2)
t = 2 * 8 * 12 / ( 8 + 12 )
t = 192/ 20 = 9.6 h
t = 9.6 h
Answer:for downstream take t1 = 8hourand for upstream t2 be 12 hour respectivelyand distance between points be l also take velocity of boat as v and of water v1
Then for downstream
t1 =l/v+v1. (1)
,for upstreamt2=l/v-v1. (2)
Time reqire by boat in still water= t0=d/v. ( 3)
Now t1=l/v/l+v1/l, t2=l/v-v1
1/t1=v/l+v1/l,1/t2=v/l-v1/l
Adding both
1/t1+1/t2=2v/l
V/l=1/2(1/t1+1/t2)
L/v=2/(1/t1+1/t2)
t0=2/(1/t1+1/t2)
Explanation:put the values of t1 qnd t2