  ### Question 31335  Verified

Gravitation

Which of the following are two explanations scientists use to explain the redshift seen in light from far away stars?

Explanation 1

Explanation 2

### Question 31334  Verified

Gravitation

The redshift seen in the light from far away stars has been offered as evidence to support the Big Bang theory.

But what is the Big Bang theory? Check out this video to learn more.

For each milestone, put in context the time from the Big Bang (t=0).

3D) The Sun forms at about t = 9.1

3A) The first nuclei (H and He) form at about t = 5

3B) The first atoms form at about t = 400

3E) We are born at about t = 13.77

### Question 31333  Verified

Gravitation

Organize the following concepts from largest to smallest, with largest on top.

### Question 31332  Verified

Gravitation

How have scientists determined the age of the universe? Well, the redshift data helped.

If you recall from an earlier tutorial, Hubble tweaked the redshift data to communicate the recessional velocity of the stars.

In other words, he calculated, based on the redshift data, how quickly the stars seem to be moving away from us.

He then plotted the recessional velocities on the y axis against distance from Earth on the x axis. The slope of the line produced from this data is referred to as the Hubble Constant, and is given the symbol Hg. This number is still under dispute, but is thought to be somewhere around 70km/s/Mpc (70 kilometers per second per megaparsec).

This value provides the rate of expansion of the universe. The inverse of this constant offers on estimate of the age of the universe.Calculate it for yourself - what is the approximate age of the universe?

### Question 31331  Verified

Gravitation

Let's recap what we've been learned from the previous tutorials:

Use the information from the video to answer these questions:

1A) What is the period of a Cepheid star used to directly determine?

1B) How do the light spectra from far away stars compare to our expected spectra?

1C) Which is true about the red shift seen in the light from far away stars?

### Question 31169  Verified

Gravitation

An object moves freely at 90° to the direction of a gravitational field.

The acceleration of the object is *

) in the direction of the gravitational field.

zero

opposite to the direction of the gravitational field.

O at 90° to the direction of the gravitational field.

### Question 31168  Verified

Gravitation

The gravitational force between point-mass objects X and Y is F1. The mass of X increases and the distance between X and Y is halved.

Which statement about the new gravitational force F2 between these two objects is correct? *(1 Doint)

O F2= F1

O F2 > 4F1

O 2F1 < F2 < 4F1

O 0 < F2 < 0.25F,

### Question 31167  Verified

Gravitation

An oscillator is forced to oscillate at different frequencies. The graph of amplitude A against the driving frequency f for this oscillator is shown.

The damping on the oscillator is now DECREASED. Which of the following statements is/arecorrect?

1. The amplitude of the oscillations at any frequency decreases.

2. The maximum amplitude occurs at a lower frequency.

3. The peak on the graph becomes thinner. *

O Statement 1 is only correct

O Statement 3 is only correct

O All three statements are correct.

Statement 2 is only correct

### Question 31166  Verified

Gravitation

Two identical springs of stiffness k are connected first in series and then in parallel. They support a mass m and are set to oscillate vertically. Evaluate the following fraction: *

O 2

O 4

2

4

### Question 31165  Verified

Gravitation

Comparing the earth's force of attraction for an object that is

a) at the surface of the earth

b) 160 km above the earth's surface

Use suitable data from the AQA Formula booklet on page 1 to evaluate *

\frac{F_{160}}{F_{\text {sufface }}} \text {, where } F_{160}=\text { Force on the object } 160 \mathrm{~km} \text { above the surface of the earth }

O 0.900

O 0.952

0.823

O 0.980

O 1.050

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