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maths questions (1 Viewer)

dawso

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gday all, i got these two questions, need help, cheers

first one is off hsc online so i hav a solution but still dont get it??

A proton travelling at 5.0 x 104 m s-1 enters a magnetic field of strength 1.0 Tesla at 90°. Determine the magnitude of the force experienced by the proton.

http://www.hsc.csu.edu.au/physics/core/implementation/9_4_1/941net.html#net10
its up there with a solution?? just check it, can anyone see any reason y it is 5 times ten to the 3 and not 4??? typo?? or my stupidity??

also....

"A photon of blue light has a wavelength of 450 nm, calculate the momentum of the photon..."

cheers

-dawso
 

kami

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CSU said:
A proton travelling at 5.0 x 104 m s-1 enters a magnetic field of strength 1.0 Tesla at 90°. Determine the magnitude of the force experienced by the proton.
With this question, the solution has a typo I think, because if you check the result against the process it seems like they are using 4 in their calculations even though they put down 3 in the working...unless I completely missed your point.
 

KFunk

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dawso said:
gday all, i got these two questions, need help, cheers

first one is off hsc online so i hav a solution but still dont get it??

A proton travelling at 5.0 x 104 m s-1 enters a magnetic field of strength 1.0 Tesla at 90°. Determine the magnitude of the force experienced by the proton.

http://www.hsc.csu.edu.au/physics/core/implementation/9_4_1/941net.html#net10
its up there with a solution?? just check it, can anyone see any reason y it is 5 times ten to the 3 and not 4??? typo?? or my stupidity??

also....

"A photon of blue light has a wavelength of 450 nm, calculate the momentum of the photon..."

cheers

-dawso

For the first one, they made a typo.

For the second:

Consider E = mc2 ---hence----> m = E/c2

p= mv
p = (E/c2).v from above

since the velocity of EMR is always c, v=c so:

p = E/c

a more convenient way of expressing this may be

p = h/wavelength since E = hf = h(c/wavelength)

p = (6.63 x 10-34)/(450 x 10-9)
= 1.473 x 10-27 kg.m/s



EDIT: Forgot units :p
 
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