ANSWER:
250 J
STEP-BY-STEP EXPLANATION:
F = 20N is required to stretch the spring by 4 meters
We know that the force is equal to:

We solve for k (spring constant):

The work done in stretching the spring is given by the following equation (in this case the stretch is 10 meters:

The work required is 250 joules.
Answer:
General circulation model.
Explanation:
A general circulation model (GCM) is a type of climate model that employs a mathematical model of the general circulation of a planetary atmosphere or ocean. GCM uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources (radiation, latent heat). These equations are the basic equations for computer programs used to simulate the Earth's atmosphere or oceans.
Answer:
The identifying characteristics are zero electrical resistivity below a critical temperature, zero internal magnetic field and a critical magnetic field above which superconductivity ceases.
Explanation:
Superconductor material classes include chemical elements (example: mercury or lead)