Why might farmer plant purebred crop seeds?

Substances that assume the shape of their container, but do not have a definite size are called

You want to move a heavy box with mass 30.0 kg across a carpeted floor. you pull hard on one of the edges of the box at an angle 30∘ above the horizontal with a force of magnitude 240 n, causing the box to move horizontally. the force of friction between the moving box and the floor has magnitude 41.5 n . what is the box's acceleration just after it begins to move

What is a analogy for transition metals