Answers to Science Teasers

  • Answer to Science Teaser #1

    He should raise his sails, since he can then tack into the wind. The apparent wind to the pirate is a 3-knot headwind since he is traveling with the current. Tacking is a way that a sailor can arrange the sails to sail almost directly into the wind. He could zig-zag down the river slightly faster than the current by using this technique. Hopefully those chasing him aren't so clever.

  • Answer to Science Teaser #2

    Bobby should choose to stay for one year. On Venus, a year (one full orbit around the Sun) is 224.7 Earth days, and a day (a full rotation of the planet) is 243 Earth days. This means that a day is longer than a year on Venus!

  • Answer to Science Teaser #3

    First, place one end of the little piece of string on top of the ice. Second, sprinkle some salt on the ice. The salt will cause the ice to melt and refreeze around the string. Now you can lift out the cube and win your free lunch.

  • Answer to Science Teaser #4

    Fire. If you light the bottom of a rope, it will quickly climb the rope. If you light the top of the rope, it will take some time for it to reach the bottom. Ever wondered why a candle will burn for so long? (Of course the wax also helps.)

  • Answer to Science Teaser #5

    You should choose the three thin blankets. This is because air acts as an insulator, so the layer of air captured between the thin blankets will increase the total insulation and keep you warmer.

  • Answer to Science Teaser #6

    The cable will be stronger because as a material is made into smaller and smaller fibers, the chance for defects causing a major failure decreases. Think of it this way: Cut a quarter of the way through the rod, and do the same to the cable. With the cable, three quarters of the wires will still be in perfect condition. The rod, however has a large crack in it now, and it is very easy to break something when there is already a crack started.

  • Answer to Science Teaser #7

    In the movies you almost always hear the sounds of objects exploding or spaceships firing lasers. Since sound can't travel in a vacuum, including outer space, this is impossible.

  • Answer to Science Teaser #8

    When liquids are mixed, the molecules can arrange themselves so that they fit together more tightly than either of the original, pure liquids. A good way to visualize this is to picture a box completely filled with billiard balls (representing large molecules). If you pour sand (representing small molecules) into the box, the sand will fill the voids between the billiard balls. The mass in the box will increase, but the total volume will not change. Jimmy can prove his innocence by weighing the mixture. His combination of liquids will equal the original weight of the water plus the weight of the ethanol.

  • Answer to Science Teaser #9

    The balloon will sink. At a depth of 60 feet, the water pressure is greater than it is at 30 feet (by about 15 psi). Because of this, the balloon will shrink, causing the balloon/weight system to increase in density (the total volume will become smaller while the total mass stays the same). Since the system is now more dense than it was at 30 feet, it will sink. Also important is the fact that since water is pretty much incompressible, the water density at both depths will be about the same.

  • Answer to Science Teaser #10

    Heat. “Powdered water” is of course finely crushed ice, and to get what you really want (liquid water), you only need to add heat.

  • Answer to Science Teaser #11

    Since the moon has no atmosphere, it is already under vacuum. The reason a vacuum cleaner works is that the pressure drop between the air in the room and the vacuum bag causes air to rush into the bag, carrying dust and dirt with it. Since there is no pressure drop between the vacuum chamber and the moon's surface, you could not suck up moon dust with a vacuum cleaner.

  • Answer to Science Teaser #12

    He can boil the water by applying a vacuum to the container. Boiling occurs when the molecules in a liquid begin to fly about independently — typically heat is added to give the particles more energy, but changes in pressure will also affect them. Once the pressure is low enough, it will no longer hold the molecules in place. So as the pressure drops, the boiling point will also drop. The water will eventually boil without gaining any heat — it will remain at room temperature. The scientist can then quickly relieve the vacuum and pour the water over his head without worry of scalding himself.

  • Answer to Science Teaser #13

    The third unit, which analyzed the contents of the chamber, is definitely a fake. “Air” is a name that we give to the combination of gasses that make up our atmosphere. It is made up of oxygen, nitrogen, carbon dioxide, and trace amounts of several other chemicals. Because of this, there is no such thing as one molecule of air. If there really is only one molecule in the chamber, it would be a molecule of oxygen, nitrogen, or one of the other chemicals. A piece of analysis equipment would never call it “air.”

  • Answer to Science Teaser #14

    The only reason that the scientist could see the assistant's hand is that light from the sun reflected off the hand and traveled to the scientist's eye. This light that allowed him to see the hand travels at the same speed as the light from the flashlight. If light traveled slowly, the scientist would still see the hand go up at the same time as he saw the light get turned on. He would just see both things happen a few seconds after they actually happened.

  • Answer to Science Teaser #15

    Because of water tension, the water at the edge of a glass will climb slightly up the inner sides. This means that the water level rises at the edges. Since ice cubes float, they will float to the highest point, which is at the edges. However, the water tension will allow you to overfill a glass just above the rim, and then the highest point will be in the center of the glass. Try it sometime.

  • Answer to Science Teaser #16

    A tightrope walker remains standing by keeping his center of mass directly above the rope. If his center of mass moves off center, he must either correct this or rotate off the rope and fall down. The balancing poles are frequently droopy and weighted at the tips. This lowers the center of mass of the performer, which also makes it easier to balance. Also, by carrying a long pole, the performer is increasing his rotational inertia. This means that he will rotate slower and therefore have more time to make a correction to his center of mass.

  • Answer to Science Teaser #17

    The balloon will actually move to the right. This is because the balloon always moves in the direction opposite to gravity. When the car is turning right, the apparent gravity is away from the center of the turn. This is why Bobby falls to the left. The balloon does the opposite.

  • Answer to Science Teaser #18

    Dan suffocated because the air that he exhaled up the pipe could not travel far enough before he inhaled it back in. In other words, the volume inside the hollow walking stick was greater than the volume of Dan's lungs. Eventually he was just breathing carbon dioxide and he passed out. Don't try this at home.

  • Answer to Science Teaser #19

    The rope is not rigid, so at any point you could pull the rope up and you would have 3 extra feet of rope. If the rope was rigid and floated an equal distance above all points of the earth, you would have a gap of almost 6 inches! (To calculate this, use the equation C = 2ηr, where C = 24,901.55. Notice that adding 3 feet to C increases r by about 6 inches.)

  • Answer to Science Teaser #20

    Find the container with mercury. Pour the mercury into the tube. Since steel is lighter than mercury, the ball will float to the top and you can easily grab it.

  • Answer to Science Teaser #21

    The beer mug is more likely to crack. Because glass is a poor heat conductor, the heat will pass through the thick beer glass slowly. This will cause the glass to expand unevenly and have a much higher chance of cracking.

  • Answer to Science Teaser #22

    Nothing would happen. Fire needs oxygen to burn, and there is no oxygen in the sealed room.

  • Answer to Science Teaser #23

    Bobby took his bird onto an airplane, where it got loose and flew to the front of the cabin at 10 mph. Thus, it was traveling at a total of 410 mph.

  • Answer to Science Teaser #24

    79 psi. Pressure gauges are set to read at 0 when the pressure being measured is the same as atmospheric pressure. True 0 psi only occurs in a complete vacuum. Since atmospheric pressure is about 15 psi, then the real pressure of the original tire is 32 + 15 = 47 psi. You can now double it to get 94 psi. Accounting again for atmospheric pressure, the gauge will read 94 − 15 = 79 psi.

  • Answer to Science Teaser #25

    The hollow jawbreaker has its mass distributed around its edge, while the solid jawbreakers have their mass distributed evenly. As a result, the solid jawbreakers will accelerate quicker when rolled or spun. Simply spin or roll some jawbreakers on a flat surface and take the slowest one.

  • Answer to Science Teaser #26

    No. A refrigerator needs to do something with all that heat it's sucking out of the inside of the fridge. It usually pumps it out the back. As far as the kitchen is concerned, there is no change in temperature in the long run. When you first open the door, the temperature may drop a little bit, but because of the heat coming out of the back of the refrigerator, once everything equalizes, the temperature of the room will stabilize.

  • Answer to Science Teaser #27

    The smaller balloon is exerting a greater force on the air inside. (This is why it's hardest to blow up a balloon at the beginning and easier once it's already got some air in it.) Because of this greater force, the small balloon will push all its air into the large balloon.

  • Answer to Science Teaser #28

    If you put a raisin into a glass of soda it will sink. Then, little bubbles will stick to it until it has enough to float to the surface. Once it hits the surface, the bubbles will pop and the raisin will sink again. This will happen until the carbonation runs out or you eat the raisin.

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