Reference Frames: Up and Down a River

In summary, the water spider maintains its position on the stream by darting upstream and drifting downstream. The current in the stream is 0.408 m/s relative to the shore. During the first part of its motion, the spider darts upstream 0.558 m in 0.844 s. Its velocity relative to the water during this dash upstream is 0.2531 m/s. During its drift downstream, its velocity relative to the water is 1.0691 m/s. The spider moves a distance of 0.2336 m upstream relative to the water during one cycle of this motion. The average velocity of the spider relative to the water for one complete cycle is 0.6611 m/s.
  • #1
TheDestroyer123
2
0

Homework Statement



A water spider maintains an average position on the surface of a stream by darting upstream (against the current), then drifting downstream (with the current) to its original position. The current in the stream is 0.408 m/s relative to the shore, and the water spider darts upstream 0.558 m (relative to a spot on shore) in 0.844 s during the first part of its motion. Use upstream as the positive direction.

a) Find the velocity of the water spider relative to the water during its dash upstream.
Answer in units of m/s

b) What is its velocity (relative to the water) during its drift downstream?
Answer in units of m/s

c) How far upstream relative to the water does the water spider move during one cycle of this upstream and downstream motion?
Answer in units of m

d) What is the average velocity of the water spider relative to the water for one complete cycle?
Answer in units of m/s

Homework Equations



-None-

The Attempt at a Solution



I believe I am doing this right, but when I submit my answers online, the website says they are all (a-d) wrong. Am I doing something wrong?

V(of spider relative to ground)=.558m/.844s = .6611

a) V(of spider relative to water)= V(of spider relative to ground) -V(of ground relative to water)
VSW=VSG-VGW
VSW=.6611-.408=.2531 m/s

b) VSW=VSG-(-VGW)
VSW=.6611+.408=1.0691 m/s

c)DSW=(VSW)t
DSW=(.2532)(.408)=.2336 m

d) AverageSW= (.2531+1.0691)/2 = .6611 m/s
 
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  • #2
TheDestroyer123 said:

Homework Statement



A water spider maintains an average position on the surface of a stream by darting upstream (against the current), then drifting downstream (with the current) to its original position. The current in the stream is 0.408 m/s relative to the shore, and the water spider darts upstream 0.558 m (relative to a spot on shore) in 0.844 s during the first part of its motion. Use upstream as the positive direction.

a) Find the velocity of the water spider relative to the water during its dash upstream.
Answer in units of m/s

b) What is its velocity (relative to the water) during its drift downstream?
Answer in units of m/s

c) How far upstream relative to the water does the water spider move during one cycle of this upstream and downstream motion?
Answer in units of m

d) What is the average velocity of the water spider relative to the water for one complete cycle?
Answer in units of m/s

Homework Equations



-None-

The Attempt at a Solution



I believe I am doing this right, but when I submit my answers online, the website says they are all (a-d) wrong. Am I doing something wrong?

V(of spider relative to ground)=.558m/.844s = .6611

a) V(of spider relative to water)= V(of spider relative to ground) -V(of ground relative to water)
VSW=VSG-VGW
VSW=.6611-.408=.2531 m/s
The spider moves upstream while the water flows downstream. If the velocity f the spider is positive, that of the water is negative.
You have never tried to swim upstream? you have to swim hard just to stay at the same place with respect to the ground...

TheDestroyer123 said:
b) VSW=VSG-(-VGW)
VSW=.6611+.408=1.0691 m/s

Read the question carefully:
b) What is its velocity (relative to the water) during its drift downstream?

What does drift mean ?
It is explained in the first sentence of the problem:
drifting downstream (with the current)
 

Related to Reference Frames: Up and Down a River

1. What is a reference frame?

A reference frame is a coordinate system used to describe the position and motion of objects. It serves as a frame of reference for measuring the position, velocity, and acceleration of objects.

2. How does the reference frame change when moving up or down a river?

The reference frame changes based on the observer's perspective and motion. When moving up or down a river, the reference frame will change to align with the direction of the current. This means that objects will appear to be moving differently depending on whether the observer is moving with or against the current.

3. What is the difference between relative and absolute reference frames?

Absolute reference frames are fixed, stationary coordinate systems used for measuring the position and motion of objects. Relative reference frames, on the other hand, are based on the observer's perspective and motion, and can change depending on the observer's frame of reference.

4. How does the concept of reference frames apply to other areas of science?

Reference frames are used in many areas of science, including physics, astronomy, and engineering. In physics, reference frames are crucial for understanding motion and forces. In astronomy, they are used to describe the position and motion of celestial objects. In engineering, reference frames are used for designing and analyzing structures and systems.

5. Can reference frames be used to explain the motion of objects in different environments?

Yes, reference frames can be used to explain the motion of objects in various environments, such as on land, in water, or in space. By understanding the reference frame of an object, we can better predict and analyze its motion in different environments.

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