A motorboat maintained a constant speed of 15 miles per hour relative to the water in going 10 miles upstream and then returning. The total time for the trip was 1.5 hours. Use this information to find the speed of the current.
Is this the correct way to put it:
10/x+15 + 10/x-15 = 1.5
2007-06-07 21:16:26 · 6 answers · asked by a100 1 in Science & Mathematics ➔ Physics
While upgoing upstream, the boat has a velocity of 15 - x mph and so takes 10/(15 - x) hours and while coming back, since its velocity is 15 + x miles per hour, it will take 10 / (15 + x) hours. The total is 1.5 hours.
So your equation is correct and let us solve it:
10 / (15 - x) + 10 / (15 + x) = 1.5
10 (15 + x) + 10 (15 - x) = 1.5 (15^2 - x^2)
150 + 150 = 1.5 X 225 - 1.5 x^2
300 - 337.5 = - 1.5x^2
x^2 = 37.5/1.5 = 25
x = 5 miles per hour
While going upstream, the boat has an effective speed of 10 mph and takes 1 hour to cover the distance of 10 miles and while returning downstream, it does the journey in half an hour at a speed of 20 mph.
2007-06-07 21:49:54 · answer #1 · answered by Swamy 7 · 0⤊ 0⤋
You are correct.
Think of the following method also.
In 1.5 hour the boat could travel 1.5 x 15 = 22.5 mile.
The actual distance traveled is 2x10 = 20.0 mile.
The distance lost due the stream flow = 2.5 mile.
The ratio of distance lost to the ideal distance
= 2.5 / 22.5
= 1/ 9
If x is the speed of the stream,
the ratio of speed of stream to that of the boat is x/15.
This ratio is equal to the √ (The ratio of distance lost to the ideal distance) = 1/ 3. (Prove this statement)
X = 15/3 = 5 miles / hour
2007-06-08 15:39:33 · answer #2 · answered by Pearlsawme 7 · 0⤊ 0⤋
All rotational action is speeded up (non-uniform velocity) via fact acceleration includes transformations in path. So regardless of if the orbits have been desirable circles (uniform tangential velocity) the action continues to be speeded up. it fairly is desirable to Euclidean (flat) area geometry in easy terms. To be technically precise, in accordance to the final concept of relativity, area around a great physique isn't flat, and orbiting gadgets stick to "geodesics" interior the curved area, that are the equivalent of quickly strains in flat area (i.e they're the shortest distance between factors). From that attitude, orbiting gadgets are following "quickly" strains and as a result are no longer accelerating. subsequently they adventure no stress.
2016-11-07 22:39:54 · answer #3 · answered by ? 4 · 0⤊ 0⤋
Looks 'bout right to me. After you do the algebra, you're going to have a quadratic equation to solve. Think about the physical meaning of having a positive and negative answer ☺
Doug
2007-06-07 21:23:35 · answer #4 · answered by doug_donaghue 7 · 0⤊ 0⤋
You're right so far, t's just a matter of solving it now.
2007-06-07 21:20:01 · answer #5 · answered by dudara 4 · 0⤊ 0⤋
yes its correct. now u only have to solve it!!!
2007-06-07 22:08:07 · answer #6 · answered by Abhinav 2 · 0⤊ 0⤋