A person is pushing a box across a table. The measured forces on the box are 10N, 14N, -7N, -10N. Which force is represented by -7N? force of friction
normal force
force of gravity
push force

An engineer decides to use a slightly weaker material rather than a stronger material, since she knows that the stronger material can break suddenly. this is an example of what? a choosing a material that will show warning before it fails b using composite materials that combine strength c using a material for multiple applications d using design techniques that increase efficiency and reduce cost