# chapter 27.1

## chapter 27.1

anyone understand how to do question # 3?

i've been trying # 3 for a while and im having no luck

i've been trying # 3 for a while and im having no luck

**phyfrk**- Guest

## Question 3

The answer to question 3 is

2.3*10^17.

Answer is neg.

The radius is constant and we use the equation

Density=Mass/Volume

So..

Density=(1.66e-27)/((4pi/3)*(1.2e-15)^3)

Gives us

2.3e17

This is constant no matter what Atomic Number is given in your problem.

2.3*10^17.

Answer is neg.

The radius is constant and we use the equation

Density=Mass/Volume

So..

Density=(1.66e-27)/((4pi/3)*(1.2e-15)^3)

Gives us

2.3e17

This is constant no matter what Atomic Number is given in your problem.

**Guest 24**- Guest

## #2

Is something wrong with MapleTA acceptiing my answer?

Atomic mass unit = 221 (given)

(221)^1/3 * 1.2*10^-15 = 7.25513*10^-15

I don't know what I am doing wrong and Allen does not have the blog updated.

Atomic mass unit = 221 (given)

(221)^1/3 * 1.2*10^-15 = 7.25513*10^-15

I don't know what I am doing wrong and Allen does not have the blog updated.

**super mo**- Guest

## Question 1

**Question 1:**

A neutron (its mass=1.67x10-27kg can be approximated as 1 u) makes an elastic head-on collision with a nucleus which is at rest and has the atomic weight 4.443 u. Calculate the velocity of the recoiling nucleus as a multiple of the velocity of the incident neutron (sheet 4). Indicate with a positive (negative) sign whether the neutron and proton masses are about equal (very different from each other).

Use the equation v_2 = ((2*m_1)/(m_1+m_2))*v_1

Let the neutron mass = m_1

Nucleus mass = m_2

Plug into the equation and you end up with v_2 = ####*v_1

That number is your answer because they ask for the velocity of the nucleus as a multiple of the velocity

Answer is

**positive**

**KT**- Guest

## Question 2

**Question 2:**

The Atomic Mass Number of a nucleus is 32. Calculate the nuclear radius in fm (sheet . Indicate with a positive (negative) sign whether the expression on sheet 8 implies that the nucleons compress or dip into each other (are considered incompressible and impenetrable).

Let A = 32

R_0 (constant) = 1.2E-15

Use the formula r = R_0*A^(1/3)

You will get something like r=#.###E-15

**m**

this answer is in meters but they want it in

**fm**

To convert to fm, know that 10^-15 meters = 1fm, so just divide your answer by 10^-15 and you will get #.###

& the answer is

**negative**

**KT**- Guest

## what is v_1 in #1?

In the formula provided for question 1, what does v_1 =?

And, we're solving for v_2, right?

And, we're solving for v_2, right?

**question**- Guest

## Re: chapter 27.1

For Question 1, v_1 is equal to the incident velocity, and yes youre solving for v_2. The question asks you to solve for v_2 as a multiple of v_1, so thats why you end up with v_2 = number*v_1

**KT**- Guest

## Re: chapter 27.1

can someone help me with #1

I can't figure it out

what do u multiply by at the end ??

I can't figure it out

what do u multiply by at the end ??

**helpp**- Guest

## #1

For # 1 you just have to convert every thing in u to kg... and then plug in the formula given above. you should get the asnwer

**ps**- Guest

## Question 3

I'm confused with Question 3 . Why is A=1? how come the radius is just the value of R_0 ?

**an0n**- Guest

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