A proton in a linear accelerator has a de Broglie wavelength of 138pm .

What is the speed of the proton?

138 pm = 138E-12 m

wavelength = h/mv

To find the speed of the proton, we can use the de Broglie wavelength formula:

λ = h / (m * v)

Where:
λ is the de Broglie wavelength
h is the Planck's constant (6.626 x 10^-34 Js)
m is the mass of the particle (in this case, the mass of a proton is approximately 1.67 x 10^-27 kg)
v is the velocity of the particle (which is what we are looking for)

Rearranging the formula to solve for v:

v = h / (m * λ)

Now, let's plug in the given values:

λ = 138 pm = 138 x 10^-12 m

Plugging these values into the formula:

v = (6.626 x 10^-34 Js) / (1.67 x 10^-27 kg) / (138 x 10^-12 m)

Calculating:

v = 3.387 x 10^7 m/s

Therefore, the speed of the proton is approximately 3.387 x 10^7 m/s.