Pinching your finger in the crack of a door on the hinge side.
Application 16. Suppose you wanted to lift a heavy frying pan off the stove. You have a cloth to keep it from burning your hand. Would it be easier to lift it by the end of the handle or by the part of the handle nearest the pan?
Application 17. A boy was going to wheel his little sister in a wheelbarrow. She wanted to sit in the middle of the wheelbarrow; her brother thought she should sit as near the handles as possible so that she would be nearer his hands. Another boy thought she should sit as near the wheel as possible. Who was right?
Application 18. James McDougal lived in a hilly place. He was going to buy a bicycle. "I want one that will take the hills easily," he said. The dealer showed him two bicycles. On one the back wheel went around three times while the pedals went around once; on the other the back wheel went around four and a half times while the pedals went around once. Which bicycle should James have chosen? If he had wanted the bicycle for racing, which should he have chosen?
Application 19. A wagon stuck in the mud. The driver got out and tried to help the horse by grasping the spokes and turning the wheel. Should he have grasped the spokes near the hub, near the rim, or in the middle?
Inference Exercise
Explain the following:
71. When you turn on the faucet of a distilled-water bottle, bubbles go up through the water as the water pours out.
72. A clothes wringer has a long handle. It wrings the clothes drier than you can wring them by hand.
73. You use a crowbar when you want to raise a heavy object such as a rock.
74. Sometimes it is almost impossible to get the top from a jar of canned fruit unless you let a little air under the edge of the lid.
75. It is much easier to carry a carpet sweeper if you take hold near the sweeper part than it is if you take hold at the end of the handle.
76. You can make marks on a paper by rubbing a pencil across it.
77. A motorman sands the track when he wishes to stop the car on a hill.
78. On a faucet there is a handle with which to turn it.
79. Before we pull candy we butter our fingers.
80. You can scratch glass with very hard steel but not with wood.
Section 11. Inertia.
Why is it that if you push a miniature auto rapidly, it will go straight?
Why does the earth never stop moving?
When you jerk a piece of paper from under an inkwell, why does the inkwell stay still?
When you are riding in a car and the car stops suddenly, you are thrown forward; your body tends to keep moving in the direction in which the car was going. When a car starts suddenly, you are thrown backward; your body tends to stay where it was before the car started.
When an automobile bumps into anything, the people in the front seat are often thrown forward through the wind shield and are badly cut; their bodies keep on going in the direction in which the automobile was going.