maths questions (1 Viewer)

[dawso]

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]

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]

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