An electron has a linear momentum of 4.0 × 10-25 kg m s-1 . What is the order of magnitude ofthe kinetic energy of the electron?

To find the order of magnitude of the kinetic energy of the electron, we can use the formula for kinetic energy:

K.E. = 1/2 mv^2

However, we don't have the velocity (v) of the electron. We do have the linear momentum (p), which is related to the mass (m) and velocity (v) by the formula:

p = mv

We can rearrange this formula to solve for v:

v = p/m

The mass of an electron (m) is approximately 9.11 × 10^-31 kg. The given linear momentum (p) is 4.0 × 10^-25 kg m s^-1. Substituting these values in:

v = (4.0 × 10^-25 kg m s^-1) / (9.11 × 10^-31 kg) = 4.39 × 10^5 m/s

Now we can substitute m and v into the kinetic energy formula:

K.E. = 1/2 (9.11 × 10^-31 kg) * (4.39 × 10^5 m/s)^2 = 8.8 × 10^-20 J

So, the order of magnitude of the kinetic energy of the electron is -20.