units

[butteredbread]

This might be too obvious or basic of a question, but can someone explain why some units have a negative one as an exponent and others don't? How do we know when to add it to our units and where?

[grace salvestrin 1J]

Hi Valeria!

I think you are talking about something like m.s^-1 for example? If this is what you mean, then you just have to memorize the units for each constant if it is not given on the equations sheet. All that this negative exponent means is that it is the units PER unit (like meters per second in the example), it’s just another way of writing the label without putting units in the denominator.
Hopefully this helps!

[Jessica Arcos 2H]

Some units have a negative one as an exponent because it just another way of showing that it's per unit. For example m*s^-1 is the same thing as m/s because s^-1 means that s will be part of the denominator.

[Janice Hu 2L]

When a unit has a negative exponent, it just means it goes in the denominator, as said before. I don't think you would ever be required to use negative exponents to express your units (for instance, you could probably use m/s or m*s^-1, as they both mean the same thing), but I'm not sure whether Dr. Lavelle prefers us to use them.

[Alice Weber 3I]

Hi Valeria! So when there is a negative one in the unit, this just means the second abbreviation goes in the denominator. So m.s^-1 is m/s which means meters per second.

[Michael 1G]

When a unit has a negative exponent (like s^-1) it means it goes in the denominator of the unit. For example, this means that a velocity, like meters per second can either be written as m/s or m*s^-1.

[205793570]

I am probably missing a key point from the lectures but I always see that we use a 9.1x10^-31, What does it represent? when do we use exactly?

[505706331]

I am probably missing a key point from the lectures but I always see that we use a 9.1x10^-31, What does it represent? when do we use exactly?

if I remember correctly I think that is the mass of an electron. this value is also on the constants and equation sheet.

[505706331]

a unit with a negative exponent like s^-1 simply just means it is "per" unit, so for this it would be per second.

[Polo Morales 3C]

Having a (-1) as an exponent is a different way of putting the base in the denominator. (Ex: 2^(-1) is the same and 1/2) Likewise, a unit with a (-1) as an exponent is the same as "per unit". Ex: m*s^-1 = m/s = meters per second. Hope this helps!

[005778617]

Like everyone else had said above, the negative exponent may sometimes mean that it is per something. For example, m.s^-1 would mean meters per second.