Như thế nào là định luât 2 niuton

An observer that stands still as the electron moves by him, will observe

What type of force holds atoms together in a crystal?

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