We all know that surfaces are able to “hold back” when carrying stuff and when burdened, squeezed or pushed. If they couldn’t, they would break.
- A table holds up a book with a “holding up” force and
- a wall holds back sideways against you leaning on it with a “holding back” force.
- ‘Online Etymology Dictionary’ (dictionary), Douglas Harper, www.etymonline.com
- ‘Sears and Zemansky’s Univesity Physics with Modern Physics’ (book), Hugh D. Young & Roger A. Freedman, Pearson Education, 13th ed., 2012