Measured speed vs actual speed very simple

  • Thread starter Thread starter asfd
  • Start date Start date
  • Tags Tags
    Speed
AI Thread Summary
When measuring the speed of a moving object using two detectors, one aligned with the movement and the other at an angle, the angled detector perceives a larger speed due to the geometry of the situation. This occurs because the hypotenuse of a triangle is longer than its sides, leading to a projection of the velocity vector that appears greater. To calculate the actual speed difference, additional information such as the angle of the detector and the distance between the detectors is needed. The projection of the velocity vector onto the angled detector results in a magnitude that is less than or equal to the original speed. Understanding these principles is crucial for accurate speed measurements in various applications.
asfd
Messages
24
Reaction score
0
Measured speed vs actual speed **very simple**

If we measure the speed of a moving object with two movement detector positioned as on the atttached drawing, i.e. one is facing the movement and the other makes a slight angle with the movement, does the detector not directly in the movement line "sees" a bigger speed since if we see this as a trinangle the hypotenuse is bigger than any other side. If so how can we calculate the difference(what other info do we need?)?
 

Attachments

  • schema.gif
    schema.gif
    2.2 KB · Views: 519
Physics news on Phys.org
asfd said:
If we measure the speed of a moving object with two movement detector positioned as on the atttached drawing, i.e. one is facing the movement and the other makes a slight angle with the movement, does the detector not directly in the movement line "sees" a bigger speed since if we see this as a trinangle the hypotenuse is bigger than any other side. If so how can we calculate the difference(what other info do we need?)?

The out of line detector sees the projection of the velocity vector onto the broken line. The magnitude of the projection is less than or equal to the original vector.
 
The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
Thread 'Beam on an inclined plane'
Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...

Similar threads

Back
Top