A 20kg box is dropped 13m. how much work is done

w = 2550.6[J]

Explanation:

We have to remember the definition of work, which is defined as the product of force by the distance travelled.

For this case we have that the force is equal to the product of the mass by the acceleration of gravity

F = m*g

where:

m = 20[kg]

g = 9.81[m/s^2]

Therefore

F = 20*9.81

F = 196.2[N]

And work is given by:

W = F*d

Where:

F = force = 196.2[N]

d = distance = 13 [m]

W = 196.2*13

W = 2550.6[J]

d) the number of neutrons plus the number of protons