A man swims upstream with 4 kmph and downstream with 10kmph
through the same path Find his average velocity
Answers
Q 1 - Speed of boat in still water is 16 km/hr. If the speed of the stream is 4 km/hr, find its downstream and upstream speeds.
A - 15,5
B - 20,12
C - 10,6
D - 18,10
Answer - B
Explanation
Downstream Speed = u + v = 16 + 4 = 20 km/hr
Upstream Speed = u - v = 16 - 4 = 12 km/hr
Q 2 - A man can row downstream at 18 km/hr and upstream at 12 km/hr. Find his speed in still water and the rate of the current.
A - 16,3
B - 15,4
C - 15,3
D - 16,4
Answer - C
Explanation
Speed of the boat or swimmer in still water = 1/2 * (Downstream Speed + Upstream Speed)
= 1/2 * (18+12)
= 15 km/hr
Speed of the current = 1/2 * (Downstream Speed - Upstream Speed)
= 1/2 * (18-12)
= 3 km/hr
Q 3 - A man swims downstream 28 km in 4 hrs and upstream 12 km in 3 hrs. Find his speed in still water and also the speed of the current.
A - 5,2
B - 5.5,1.5
C - 5.5,2.5
D - 5,1
Answer - B
Explanation
Downstream Speed (u) = 28/4 = 7 km/hr
Upstream Speed (v) = 12/3 = 4 km/hr
Speed of the boat or swimmer in still water = 1/2*(Downstream Speed + Upstream Speed)
= 1/2*(7+4)
= 5.5 km/hr
Speed of the current = 1/2*(Downstream Speed - Upstream Speed)
= 1/2*(7-4)
= 1.5 km/hr
Q 4 - The speed of the boat in still water is 15 km/hr. It takes twice as long as to go upstream to a point as to return downstream to the starting point. What is the speed of the current?
A - 4 km/hr
B - 3 km/hr
C - 2 km/hr
D - 5 km/hr
Answer - B
Explanation
Let speed of the current = S km/hr.
As per question,
Downstream Speed = 2*Upstream speed
15 + S = 2(15 - S)
S = 3 km/hr
Q 5 - A boat covers a certain distance downstream in 6 hours and takes 8 hours to return upstream to the starting point. If the speed of the stream is 3 km/hr, find the speed of the boat in still water.
A - 1 km/hr
B - 4 km/hr
C - 3 km/hr
D - 2 km/hr
Answer - C
Explanation
t1 = 6 hrs
t2 = 8 hrs
v = 3 km/hr
u = ?
We know,
(u + v)t1 = (u - v)t2
(u + 3)6 = (u - 3)8
u = 3 km/hr
Answer:
A man swims upstream with 4 kmph and downstream with 10kmph
through the same path Find his average velocity