Question

急！！！！！！！美国高中的物理题，中国初中水平左右，请用英语回答并且写下过程，谢谢 （第2,4-7

急！！！！！！！美国高中的物理题，中国初中水平左右，请用英语回答并且写下过程，谢谢 （第2,4-7题）

Answer 1

我给你答，不过你得等到我发完再采纳可以吗？

追答

2. below

because there will be light refraction happens when the light goes through the surface of water, Jessica would tell the one to aim slightly below the fish.

4. on the slope, regardless of friction, acceleration of the person would be a=gsin40°≈6.3m/s², and the final velocity at 100 meters would be v=square root of (2×6.3×100)≈35.5 m/s

apply speed of sound as 344m/s, then the distance is d=344×15=5160m

第二条是第五题

6. because they have different kinds of vibration to make the note.

7. according to conservation of energy,

if he starts from rest, mgh=0.5mv², 9.8×3=0.5×v²，v≈7.67m/s

If he has an initial velocity which can make him finally 0.5m higher than the start point, 3.5mg=0.5mv0²+3mg, v0=1m/s

If he starts from rest, yes, he violates the coservation, because the energy he would get on the 3.5m location is more than that of 3.0m, which is the initial energy.

If he starts with a speed v=1m/s, he doesn't.