So in this situation there is a net force in the rightward direction.

现在考虑更多的例子。

So you have zero net force, these right here are balanced.

现在考虑更多的例子。

Or their must not be any net force.

或者肯定没有合力。

Because they're balanced there is no net force and this rock isn't going to accelerate.

现在考虑更多的例子。

So maybe that's the net force that's causing the move.

不要认为 运动就存在合力作用 记住 这非常重要。

So once again what is the net force here?

首先还是看合力是多少？

So once again these are all balanced forces or there's no net force going on right over here.

现在考虑更多的例子。

The acceleration equals the net force divided by the mass.

加速度等于净力除以质量。

Acceleration is gonna be the net force divided by the mass.

加速度将是净力除以质量。

So for example, we have a net force acting leftward on this large asteroid.

例如，我们有一个净力作用在这颗大小行星上向左。

And then we would have no net force.

然后我们就没有合力了。

So there are centripetal motion. There is some net inward force going on here.

所以有向心运动。这里有一些净内向力。

We  are going to use that fact to determine the net force acting on our hypothetical cube.

我们将利用这一事实来确定作用在我们假设的立方体上的净力。

So negative 2.45 meters per second squared is gonna equal the net force on the five kilogram mass.

所以每平方秒负 2.45 米等于 5 千克质量上的净力。

In other words: if down the ramp is the positive direction, is the net force positive or zero?

阻性辅音，换句话说：如果方向 在正斜率下，全力为 0 吗？

So when we're trying to calculate a NET force, we usually have to take into account more than just gravity.

因此，当我们尝试计算完美功率时，我们通常会 通过计算重力以外的东西。

And so the only way you can actually get this thing to come out of that rest position is if you have a net force, an unbalanced force.

因此, 使物体由静止开始运动的唯一方法就是施加一个非零净力 -- 非平衡力.

Even though there's now twice as much force being exerted on this asteroid, it's going in opposite directions, so they zero out, and so there's zero net force.

尽管现在施加在这颗小行星上的力是原来的两倍，但它的方向相反，因此它们为零，因此净力为零。