Tag: motion and measurement

Quizzes (11) Questions (114)

Questions Related to motion and measurement

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

What is the approximation made in the parallax method?

  1. All distances measured between two points on earth is zero.

  2. All distances measured between two points on earth is constant.

  3. Distance between a point on the earth and the planet is very large as compared to the distance between two points on earth's surface.

  4. No approximation is made.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In parallax method, an approximation is made that distance between a point on the earth and the planet is very large as compared to the distance between two points on the earth's surface.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

Two stars $S _1$ and $S _2$ are located at distances $d _1$ and $d _2$ respectively. Also if $d _1>d _2$ then which of the following statements is true?

  1. The parallax of $S _1$ and $S _2$ are same.
  2. The parallax of $S _1$ is twice as that of $S _2$.
  3. The parallax of $S _1$ is greater than parallax of $S _2$
  4. The parallax of $S _2$ is greater than parallax of $S _1$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Answer:-$ D

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.Due to foreshortning, nearby objects have a larger parallax than more distant objects when observed from different positions, so parallax can be used to determine distances.

Hence parallax of $S _2$ is greater than that of $S _1$

Astronomersuse the principle of parallax to measure distances to the closer stars. Here, the term "parallax" is the semi-angle of inclination between two sight-lines to the star, as observed when the Earth is on opposite sides of the Sun in its orbit.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

Parallax is the apparent displacement of an object because of:

  1. change in observer's point of view

  2. change in object's position

  3. changes both in observers point of view and object's position

  4. consistency in observer's point of view
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Astronomers use an effect called parallax to measure distances to nearby stars. Parallax is the apparent displacement of an object because of a change in the observer's point of view.

As the Earth orbits the sun, a nearby star will appear to move against the more distant background stars. Astronomers can measure a star's position once, and then again 6 months later and calculate the apparent change in position.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

Parallax method is useful 

  1. for measuring speed of the light.

  2. for measuring distances of star.

  3. for finding the intensity of the light.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Answer:-$ B

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. Astronomers use the principle of parallax to measure distances to the closer stars.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

To minimise parallax error, the observer should place the object :

  1. as near to the scale of the ruler as possible and the eye must be directly above the scale

  2. as far to the scale of the ruler as possible and the eye must be directly above the scale

  3. as near to the scale of the ruler as possible and the eye must be to the right of the scale

  4. as near to the scale of the ruler as possible and the eye must be to the left of the scale
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$Answer:-$ A

There are three simple ways of reducing parallax error in that case: 
1. Attach a straight object (like a ruler or straightened paperclip) to the thing you're measuring the displacement of, it should stick out of the object perpendicularly to the scale you're measuring the displacement on. 
2. Make sure that object is as close to your scale as possible, but not touching. 
3. Put your eyes level with the object, and as close to it as you safely can.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

The effect of parallax is used to measure:

  1. distances to nearby objects

  2. distances to nearby stars

  3. nearness of atoms in substances

  4. the object and image distance in optical experiments
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Astronomers use an effect called parallax to measure distances to nearby stars. Parallax is the apparent displacement of an object because of a change in the observer's point of view.

As the Earth orbits the sun, a nearby star will appear to move against the more distant background stars. Astronomers can measure a star's position once, and then again 6 months later and calculate the apparent change in position.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

A star has a parallax angle p of 0.723 arcseconds. What is the distance of the star?

  1. 1.38 parsecs

  2. 2.38 parsecs

  3. 3.38 parsecs

  4. 4.38 parsecs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Relationship between a star's distance and its parallax angle:

$d=\dfrac{1}{p}$

The distance $d$ is measured in parsecs and the parallax angle $p$ is measured in arcseconds.

Hence, $d=\dfrac{1}{0.723}=1.38 parsecs$

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

Error due to eye vision is termed as :

  1. climax error

  2. sight error

  3. parallax error

  4. visional error
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Answer:-$ C

Parallax also affects optical instruments such as rifle scopes, binoculars,microscope and twin lens reflex cameras that view objects from slightly different angles. Many animals, including humans, have two eyes with overlapping visual fields that use parallax to gain depth perception; this process is known as stereopsis.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

A star's distance ($d$) and its parallax angle ($p$) are related to each other as:

  1. $d=\dfrac{1}{p}$
  2. $d=\dfrac{1}{p^2}$
  3. $p=\dfrac{1}{d^2}$

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Astronomers use an effect called parallax to measure distances to nearby stars. Parallax is the apparent displacement of an object because of a change in the observer's point of view.

The relationship between a star's distance and its parallax angle:

$d=\dfrac{1}{p}$

The distance $d$ is measured in parsecs and the parallax angle $p$ is measured in arc seconds.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

Parallax method is based on which of the following principle?

  1. Disparity

  2. Lutz Kelker bias

  3. Trilateration

  4. Triangulation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Distance measurement by parallax is a special case of the principle of triangulation, which states that one can solve for all the sides and angles in a network of triangles if, in addition to all the angles in the network, the length of at least one side has been measured. Thus, the careful measurement of the length of one baseline can fix the scale of an entire triangulation network. In parallax, the triangle is extremely long and narrow, and by measuring both its shortest side (the motion of the observer) and the small top angle (always less than 1 arcsecond leaving the other two close to 90 degrees), the length of the long sides can be determined.