A chef places an open sack of flour on a kitchen scale. The scale reading of 40N indicates that the scale is exerting an upward force of 40N on the sack. The
magnitude of this force equals the magnitude of the force of earth’s gravitational
attraction on the sack. The chef then exerts an upward force of 10N on the bag and
the scale reading falls to 30N. Draw a free-body diagram of the latter situation.