2019学年度译林版选修七Unit2Period2Task阅读教案设计

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Science experiments are a fun way for kids to learn all about science. I will introduce a few great experiments and teach your child all about the wonders of inertia (惯性)．

Coin Shoot

You'll need some coins, at least eleven, and a smooth table. Stack (堆叠) all but one of the coins on the smooth table, making sure that the "high rise" is straight. Coins with wide edges make this experiment easy to do. Flick (弹) the extra coin quickly towards the bottom of the stack so that it hits the bottom coin. The bottom coin from the stack should shoot out from under the other coins without changing the rest of the stack. With good aim and quick flicks of your finger, you should be able to shoot all of the coins out of the stack one by one. Because the inertia of the stack of coins is so great, the force from the flicked coin is not enough to make the entire stack move or fall down.

The Pencil Standing

Place a narrow piece of paper on a smooth table. Hold the paper so that most of it hangs off the table. Place a pencil on the paper so that it is standing straight. Now, slowly try to pull the paper out from under the pencil. What happens? Set up the paper and pencil again, and give the paper a fast pull. What happens to the pencil this time?

Since the still pencil wants to stay at rest, it will be against the fast movement of the paper. This means that when the paper is moved quickly out from under the pencil, the pencil remains standing straight. If the paper is moved slowly, the movement has a chance to influence the pencil, and it will fall down.

21．What do we know about stacking the coins?

A．At least eleven coins are needed but one isn't stacked.

B．The more coins in the experiment, the better.

C．All the coins should be stacked straight.

D．Nine coins are stacked but two are not.

22．What result can we get if we do the first experiment well?

A．The stack of coins fall down on the table.

B．The bottom coin is flicked out of the stack.

C．All of the coins are taken away from the table.

D．All of the coins are shot out of the stack one by one.

23．Most of the paper hangs off the table so that ________.

A．we can pull it quickly

B．we can take hold of it

C．it can influence the pencil

D．the pencil can stand straight

24．If we pull the paper slowly out from under the pencil, the pencil will ________.

A．move slowly with the paper

B．stand straight on the table

C．be shot out from the table

D．fall down on the table