Find Kmax with given numerical quantities

[xpaulinabearx]

Homework Statement

K(max) = (6.63x10^-34 J s)(7.09x10^14s) - 2.17x10^-19J
solve for kmax

Homework Equations

none?

The Attempt at a Solution

K = (6.63x10^-34 J s)(7.09x10^14 s) - (2.17x10^-19 J)
K = (6.63)(7.09)(10^-34)(10^14) J s^2 - (2.17x10^-19 J)
K = (47.0067)(10^-24) J s^2 - (2.17x10^-19 J)
K = (4.70067x10^-23) J s^2 - (2.17x10^-19 J)
K = J [ (4.70067x10^-23) s^2 - (2.17x10^-19) ]
K = J (10^-19) [ (4.70067x10^-4) s^2 - 2.17 ]

 

[vela]

-34+14 = ? (It's not -24.)

 

[xpaulinabearx]

oh shoot, stupid mistake! haha, thanks for the catch!

 

[gneill]

Homework Statement

K(max) = (6.63x10^-34 J s)(7.09x10^14s) - 2.17x10^-19J
solve for kmax

The expression doesn't make sense from the outset: the units being added are not consistent.
(J*s)*s = J*s², which is not the same as J alone, so these items cannot be added together meaningfully.

Perhaps the first item should be (6.63x10^-34 J s^-1) ?

 

[vela]

The first constant is Planck's constant, which does have units of J s. The second quantity is supposed to be a frequency, with units of s^-1. Probably just a typo on the OP's part.