How does a hammer make it easier to pull a nail out of a board? First, it changes the direction of the force applied to the hammer—the hand pushes down on the handle while the claw end of the hammer head pulls up. Often, you can push down with more force than you can push up because you can put your own weight behind it. The hammer also increases the strength of the force that is applied to it. It easily pulls the nail out of the board, which you couldn’t do with your hands alone. On the other hand, the hammer decreases the distance over which the force is applied. The hand pushing down on the handle moves the handle over a distance of several inches, whereas the hammer pulls up on the nail only an inch or two.
Beth and Ann were playing on the playground. While playing Beth tried to lift Ann up but could not. Later Ann who was older and weighed more than Beth suggested they play on the seesaw. Both girls sat on opposite ends of the seesaw and started moving up and down.
Did Ann weigh less on the seesaw than she had earlier or the same?