### Units

Posted:

**Tue Oct 22, 2019 2:59 pm**I'm having trouble with units when conducting some of these problems. Could anyone help me with the units of velocity, threshold energy, Plank's constant, and frequency?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=172&t=48558

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Posted: **Tue Oct 22, 2019 2:59 pm**

I'm having trouble with units when conducting some of these problems. Could anyone help me with the units of velocity, threshold energy, Plank's constant, and frequency?

Posted: **Tue Oct 22, 2019 3:19 pm**

Velocity: meters per second

Threshold energy: Joules

Plank's constant: Joules times seconds

Frequency: Hz (which is also cycles per second)

You can also find these on the constants and equations sheet that they give us during tests:

https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf

I hope this helps!

Threshold energy: Joules

Plank's constant: Joules times seconds

Frequency: Hz (which is also cycles per second)

You can also find these on the constants and equations sheet that they give us during tests:

https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf

I hope this helps!

Posted: **Tue Oct 22, 2019 3:32 pm**

Reina Robles 1H wrote:Velocity: meters per second

Threshold energy: Joules

Plank's constant: Joules times seconds

Frequency: Hz (which is also cycles per second)

You can also find these on the constants and equations sheet that they give us during tests:

https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf

I hope this helps!

I completely agree with Reina's advice! Also, I highly recommend using the constants and equations sheet while solving homework problems to simulate a test situation. Additionally, I wanted to note that 1 Joule is equivalent to 1 kg⋅m2⋅s−2. This can help you cancel units, depending on what you're solving for. This conversion used to trip me up and it shows up a lot in the homework problems. I hope this helps!

-Rebecca

Posted: **Tue Oct 22, 2019 9:06 pm**

velocity: m/s

threshold energy: J or kg. m^2. s^-2

Planck's constant: 6.626 x 10^-34 Js or kg.m^2. s^-1

frequency: Hz or s^-1

threshold energy: J or kg. m^2. s^-2

Planck's constant: 6.626 x 10^-34 Js or kg.m^2. s^-1

frequency: Hz or s^-1

Posted: **Tue Oct 29, 2019 2:25 pm**

Thank you everyone! I didn't realize we would be provided a list of constants. It would be a good idea for me to do the practice problems with this sheet to cancel out units.