## Textbook Problem 1B27

Constance Newell
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Joined: Wed Sep 30, 2020 9:38 pm

### Textbook Problem 1B27

1B.27 A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at
5.00±5.0m⋅s−1. What is the minimum uncertainty in its position?

Could someone explain why we don't convert 8.00kg to grams in this problem

Thank you!

Sabina House 2K
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### Re: Textbook Problem 1B27

SI units are always in kg, not g. Because of this, the constant h used in the Heisenberg's indeterminacy equation is in units of J/s, and 1 J = 1 kg m^2 s^-2. Because the constant h uses kg, you must use units of kg for the mass.

Isaac Wen
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### Re: Textbook Problem 1B27

We've been using grams in the previous chapter because molar mass is in g/mol. Now, since we're no longer dealing with molar mass, we use the standard SI unit, kg!

DanielHong2L
Posts: 39
Joined: Wed Sep 30, 2020 9:51 pm

### Re: Textbook Problem 1B27

Constance Newell wrote:1B.27 A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at
5.00±5.0m⋅s−1. What is the minimum uncertainty in its position?

Could someone explain why we don't convert 8.00kg to grams in this problem

Thank you!

I'm also confused in the uncertainty in position. I thought Dr. Lavelle explained that if it was +/- 5.0 m/s then the uncertainty would be 5*2; so delta v = 10. However, the txtbook answer simply uses 5 as the delta v to calculate it.

If anyone / mods can clarify this that'll be amazing!

DanielHong2L
Posts: 39
Joined: Wed Sep 30, 2020 9:51 pm

### Re: Textbook Problem 1B27

DanielHong2L wrote:
Constance Newell wrote:1B.27 A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at
5.00±5.0m⋅s−1. What is the minimum uncertainty in its position?

Could someone explain why we don't convert 8.00kg to grams in this problem

Thank you!

I'm also confused in the uncertainty in position. I thought Dr. Lavelle explained that if it was +/- 5.0 m/s then the uncertainty would be 5*2; so delta v = 10. However, the txtbook answer simply uses 5 as the delta v to calculate it.

If anyone / mods can clarify this that'll be amazing!

Oh oops nevermind just checked other post on this same problem. They said it's a txtbook error (check on dr lavell's website answer key thing) so

tl;dr:

The uncertainty in poisition is *2 the +/- so it'd be 10 m/s because that includes both the possibility of being +5 and -5.

905290504
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### Re: Textbook Problem 1B27

for uncertainty you want to keep it in kg because planck's constant's units are J*s which is a simplification of (kg*m^2*s^-2)(s)
*** 1 J = kg*m^2*s^-2

905290504
Posts: 57
Joined: Wed Sep 30, 2020 9:44 pm
Been upvoted: 1 time

### Re: Textbook Problem 1B27

for uncertainty you want to keep it in kg because planck's constant's units are J*s which is a simplification of (kg*m^2*s^-2)(s)
*** 1 J = kg*m^2*s^-2