第一天表達積累

1 be at rest

2 it followed that

3 work?out all the laws that govern?the universe by pure thought

4 to check?by observation

6 So?no one until Galileo bothered to see

7? the leaning tower of Pisa

8 do something equivalent

9 indicate

10 let go of a ball

11 a feather is slowed down by air resistance

12 to set it moving

13 This?idea was first stated explicitly in

14 This states that the body will accelerate, or change its speed, at a rate that is proportional to?the force.

15 According to Newton’s second law, these two effects will exactly cancel each other, so the acceleration will be the same in all cases.

16 Newton’s law of gravity also tells us that

17 This law predicts the orbits of the earth, the moon, and the planets with great accuracy.

18In particular, he thought that the earth was at rest.

19 One could equally well say that body A was at rest and body B was moving at constant speed with respect to body A, or that body B was at rest and body A was moving.

20 If one carried out experiments with moving bodies on the train, all Newton’s laws would still hold.