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#### 对坠落物体的误解

Let’s say you have Jack hold both balls above his head,

and then he drops them at exactly the same time.

What do you expect to see?

Well, they’re gonna hit the ground at the same time.

I expect them to both land at the same time.

Same time.

Same time.
-我认为他们会同时……-我觉得理论上这个球会首先落地
– I think they both will…- We usually expect this one would hit the ground first.

However, they’ll actually both hit the ground the same time.

Why is that?
-科学 -对 科学
– Science.- Yeah, science.

The black one clearly feels a lot heavier.

So the standard misconception is to believe that

the black ball will accelerate at a greater rate

and reach the ground first.

This year, many people had an idea that

both balls would land at the same time,

but they didn’t know exactly why.

I found there were some different misconceptions.

For example, many people seem to think that

as an object falls towards the earth,

it falls with a constant speed.

From this thought, yeah, pretty much.

Just constant speed all right down spate.

Yeah, I think it would be the same constant speed.

I think it’s constant.

I think they never be in constant.

I did decently in physics, and I still remember that’s the answer.

Whereas the truth is the speed of both balls is changing all the time.

The balls are speeding up as they go towards the ground.

That’s what the force of gravity does on them.

It makes them accelerate.

It gets them to speed up.

Another misconception I discovered was that

some people believed both balls should have the same gravitational force on them,

even though the black ball is clearly much much heavier.

The reason I think they said this was because they knew

both balls needed to reach the ground at the same time,

so they reasoned that the force on them must be the same.

Tell me about how the gravitational force on this ball

compares to the gravitational force on that ball.

The force is the same.

It’s very very similar.

In terms of gravitational pull,

they both have the same and they’ll fall at the same rate.

I’m not like Einstein,

but same gravitational force around the whole world, right?

Because the gravitational pull on the earth is the same on both objects.

Are you saying that the force on them is the same?

The pull is the same.

But you felt the pull and you’ve told me the pull is different.

No, I said the weight is heavier, and the pull is no different.

It is heavier and has more gravitational pull.

But when I dropped them,

then they get equal gravitational pull somehow.

Do you think it’s gonna be like five times as much?

Yeah, you think, but it’s not.

The way you’re asking it, yes.

But scientifically speaking, no.
-这两个球受到的地心引力是相同的 -好吧
– The gravitational force on both these balls are the same.- Okay.

The gravitational force on both of these balls is the same.

Is that what you actually believe?
-不 但大家都这样说 -你能告诉我……
– No, but it is.- Would you tell me…

Tell me what you believe.

I believe it should be more on this.

Simply for the fact that this is heavier.

I just… intuition tells me that it should be more.

But after learning physics,

we learn that it is actually the same.

I actually think the force on this ball is more.
-真的吗？ -不骗你啦
– Indeed?- Just no kid more.

I swear. I’m not tryna mess with you.
-在现实生活中么……-在现实中和物理理论上都是
– So… in the real life and in physics.- Like in real life?

– I’ll tell you that the force on this ball is more.- All right.

-你没有说假设条件 -是同时落地
– You have no presume.- Same time.
-无论怎样 天啊 -它们是……同时落地的
– Whatever, Jesus.- They’re… the same time.

I would say the force on the medicine ball is like a lot more,

because it’s got a lot more weight.
-它的质量很大-对
– It’s got a lot more mass.- Yeah.
-但是它的惯性也更大 -哦 原来是这样
– But it’s got a lot more inertia. – Yeah, yeah. Oh.

You guys remember that, right?

It’s got a lot of resistance to acceleration,

so it takes more force

to get it accelerating at the same rate as this ball.

And that’s why they accelerate at the same rate.

Thank you guys so much. I appreciate that.
-到此结束 -拜拜
– Sorry, guys.- That’s all right.

jm

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