00:03
Okay, so in this problem, they ask, on a far, far away planet, an astronaut picks up a rock.
00:10
The rock has a mass of five kilograms, and on this planet, its weight is 40 newtons, mass times acceleration.
00:18
The astronaut exerts an upward force of 46 .2 newtons on the rock.
00:23
What is its acceleration? so, here, the trick is to remember newton's laws, in this case, the second, law force equals mass times acceleration and that the sum of the forces cause a change in acceleration.
00:45
So here we have a rock with a mass of five kilograms in a weight of 40 newtons and the astronaut is exerting a force of 46 .2 newtons.
00:55
It's important to remember that in this problem we're going to we're going to use the upward direction as positive and the downward direction as negative.
01:06
And so we can find the sum of forces as the difference between these two vectors.
01:14
So i'll grab a new sheet here.
01:18
And if you write it out, you have the sum of the forces equals.
01:27
Remember, downward is negative...