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A person can row downstream 20km in 2 hours and upstream 4km in 2 hours. find the speed of the current?
Wiki User
∙ 14y ago
To do this, you need to form equations using the information given. There are 2 variables here, the base speed of the rower with no current (x), and the speed of the current (y).
Firstly, convert the distances and times given into average speeds.
20km/2 hours = 10km/h
4km/2 hours = 2km/h
The actual speed = the base speed +- the current, depending on direction.
So 10 = x + y
2 = x - y
If we subtract these 2 equations to eliminate x, we get:
8 = 2y
y = 4km/h
Wiki User
∙ 14y ago
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A badge moves 8km per hour in still water it travels 6km upstream and 6 km downstream in a total time of 2 hours what is the speed of the current?
The speed upstream is B - C where B is the speed of the badge in still water and C is speed of the current The speed downstream is B + C. Velocity = Distance/Time : therefore Time = Distance/Velocity. Time for upstream journey = 6/(B - C) Time for downstream journey = 6/(B + C) BUT Total time for journey = 2 = 6/(B - C) + 6/(B + C) = 12B/(B2 - C2) Therefore 2B2 - 2C2 = 12B : However, B = 8kph so substituting gives, 128 - 2C2 = 96 : 2C2 = 32 : C2 = 16 : C = 4 The speed of the current is 4kph.
In still water a boat can travel four times as fast as the current in the river A trip up the river and back which totaled 150 km took 8h Find the speed of the current?
Call the unknown speed of the current c and the speed of the boat in still water b. When travelling upstream, the net speed of the boat will be b - c and when travelling downstream the net speed of the boat will be b + c. Since b = 4c, the speed upstream will be 3c. The distance upstream is one-half the total travelling distance of 150 km or 75 kilometers. Distance travelled = speed X time at speed, so that upstream time = 75/3c, downstream time = 75/5c, and the sum of these is the total time stated to be 8 hours. Thus 75/3c + 75/5c = 8. Multiplying both sides by 15c yields 75(5 +3) = 120c, or c = (8 X 75)/120 = 5 kilometers per hour.
If a boat travels upstream against a 3 mph current and travels 5 hours and the return trip takes 2.5 hours what is the speed of the boat?
Suppose the speed of the boat is x mph. Then upstream, it travels 5 hours at x-3 mph and so covers 5x - 15 miles. When going downstream the boat covers the same distance, at x+3 mph, in 2.5 hours so (5x-15)/(x+3) = 2.5 Multiply through by 2*(x+3): 2*(5x-15) = 5*(x+3) 10x - 30 = 5x + 15 or 5x = 45 giving x = 9 mph.
Julie and Eric row their boat at a constant speed 40 miles downstream for 4 hours helped by the current?
The average speed downstream is 40 ÷ 4 = 10 mph. However, it would seem that insufficient information has been supplied to enable a satisfactory answer to this question to be provided.
A motorboat maintained a constant speed of 24 miles per hour relative to the water going 35 miles upstream and then returning the total time for the trip was 3.0 hours What is the speed of current?
The current speed is about 4 miles per hour.
A motorboat takes 5 hours to travel 300 km going upstream The return trip takes 2 hours going downstream. What is the rate of the boat in still water and what is the rate of the current?
Velocity = Distance ÷ Time.The speed upstream = 300 ÷ 5 = 60kph.The speed downstream = 300 ÷ 2 = 150 kph.The speed upstream equals boat velocity(Vb) minus current velocity(Vc).The speed downstream equals boat velocity (Vb) pluscurrent velocity (Vc).Vb - Vc = 60Vb + Vc = 150 : Adding the two equations together gives :-2Vb = 210 : Vb = 105, therefore Vc = 45The rate of the boat in still water is 105 kph. The rate of the current is 45 kph.
A boat goes 16km upstream and 24 km downstream in 6 hours it covers 12km upstream and 36 km downstreamfind speed of the boat and stream?
2.2 Type your answer here...
A badge moves 8km per hour in still water it travels 6km upstream and 6 km downstream in a total time of 2 hours what is the speed of the current?
The speed upstream is B - C where B is the speed of the badge in still water and C is speed of the current The speed downstream is B + C. Velocity = Distance/Time : therefore Time = Distance/Velocity. Time for upstream journey = 6/(B - C) Time for downstream journey = 6/(B + C) BUT Total time for journey = 2 = 6/(B - C) + 6/(B + C) = 12B/(B2 - C2) Therefore 2B2 - 2C2 = 12B : However, B = 8kph so substituting gives, 128 - 2C2 = 96 : 2C2 = 32 : C2 = 16 : C = 4 The speed of the current is 4kph.
A boat on the Missouri river took 2 hours to go 48 miles downstream. The boat took 3 hours to return the same distance upstream. Find the rate of the boat in still water and the rate of the current.?
Boats speed = 24 miles per hour.Current speed = 4 miles per hour.
It takes a motor boat 3 hours to make a downstream trip with a current of 7 miles per hour the return trip against the same current took 5 hours find the speed of the boat in still water?
Since the distance downstream (with the current) equals the distance upstream (against the current), and if we: Let B stand for the speed (rate in mph) of the boat in still water, and using the formula rate X time = distance, the equation will be: (B+7) x 3 = (B-7) x 5 3B + 21 = 5B - 35 56 = 2B B = 28 mph Traveling downstream, the current will cause the boat to go faster so the 7 mph current is added to the boat's still water speed. Traveling upsteam the current slows or decreases the boat's rate so the current's speed is subtracted from the boat's still water speed.
A boat makes a 120-mile trip downstream in 3 hours but makes the return trip in 4 hours. What is the rate of the current?
It is 5 miles per hour.
In still water a boat can travel four times as fast as the current in the river A trip up the river and back which totaled 150 km took 8h Find the speed of the current?
Call the unknown speed of the current c and the speed of the boat in still water b. When travelling upstream, the net speed of the boat will be b - c and when travelling downstream the net speed of the boat will be b + c. Since b = 4c, the speed upstream will be 3c. The distance upstream is one-half the total travelling distance of 150 km or 75 kilometers. Distance travelled = speed X time at speed, so that upstream time = 75/3c, downstream time = 75/5c, and the sum of these is the total time stated to be 8 hours. Thus 75/3c + 75/5c = 8. Multiplying both sides by 15c yields 75(5 +3) = 120c, or c = (8 X 75)/120 = 5 kilometers per hour.
If Tina swims 4 miles upstream at 1 mph and back downstream to the same point at 4 mph what is her average speed?
Her average speed is 1.6 miles per hour. Average speed is total distance covered by total time taken to do it. She swims 4 miles upstream, and at 1 mph, it takes 4 hours. She comes back downstream at 4 mph and so she covers the 4 miles in 1 hour. Her total mileage is 8 miles. It takes 4 + 1 hours or 5 hours to cover it. The 8 miles divided by 5 hours is 1 3/5 miles per hour, or 1.6 mph for an average speed.
If a boat travels upstream against a 3 mph current and travels 5 hours and the return trip takes 2.5 hours what is the speed of the boat?
Suppose the speed of the boat is x mph. Then upstream, it travels 5 hours at x-3 mph and so covers 5x - 15 miles. When going downstream the boat covers the same distance, at x+3 mph, in 2.5 hours so (5x-15)/(x+3) = 2.5 Multiply through by 2*(x+3): 2*(5x-15) = 5*(x+3) 10x - 30 = 5x + 15 or 5x = 45 giving x = 9 mph.
A man rows upstream for 20 miles in 5 hours and 10 miles downstream in 2 hrs What is the speed of the man in still water?
Speed upstream(S.u) = 20/5 => 4miles/hr Speed downstream(S.d) = 10/2 => 5miles/hr Speed of man in still water(speed of boat in still water)= 1/2 * (S.u + S.d) = 0.5 * (4 + 5) = 0.5 *9 = 4.5miles/hr The speed of man in still water is 4.5 miles/hr
A fishing boat traveled 3 hours against a 6 kmhr current The return trip took only 2 hours Find the speed of the boat?
The speed of the boat is 36 km/h. Going upstream: 3h x 36km/h = 108 km, minus (6x3 =18 km) = 90 km Going downstream: 2h x 36km/h = 72 km, plus (6x2 =12 km) = 90 km
Julie and Eric row their boat at a constant speed 40 miles downstream for 4 hours helped by the current?
The average speed downstream is 40 ÷ 4 = 10 mph. However, it would seem that insufficient information has been supplied to enable a satisfactory answer to this question to be provided.
