Describe what is meant by spacetime.

Outline how the concept of spacetime accounts for the

(i) orbiting of Earth about the Sun.

(ii) nature of a black hole.

spacetime is a (4 dimensional) coordinate system/a coordinate system used to locate events;
consisting of three space coordinates and one time coordinate;

(i) the mass of the Sun causes the spacetime around it to be warped;
objects follow the shortest path/geodesic between points in spacetime;
for the Earth this an elliptical/circular path about the Sun;

(ii) black holes produce a region of spacetime with extreme curvature; } (must indicate the curvature is very large for this mark)
such that not even radiation can escape from the influence of a black hole;