00:02
For this problem, or for this section, i guess, we're just going to be filling in some things about physics.
00:09
So first, we have the law of inertia.
00:12
An object at rest, or an object will remain at rest, or move at a constant velocity, unless acted upon by an external, presumably it might be an external object or force.
00:33
But generally speaking, the law of inertia is just phrased in terms of an external force.
00:41
Then the law of acceleration, the, let's see here, the acceleration of an object is, let's see here, is directly proportional to the strength of the force acting on it and is in, inversely proportional to its mass, then the law of action and reaction, action and reaction.
01:35
And that is that in every interaction, there is an equal and opposite reaction.
01:56
Then, let's see here.
02:01
For one, we are given mass and force, and we're asked for the acceleration.
02:06
So acceleration, since we have f equals ma, acceleration is going to be f over m.
02:12
So that's 200 kilograms over 800 or 800 newton's over 200 kilograms.
02:18
So we have that the acceleration is going to be 4 meters per second squared.
02:24
Then for two, a car of mass 90 kilograms is accelerating with a constant rate of 3 .0 meters per second.
02:30
What is the net force acting on the car? it would be 9 times 3.
02:34
So, or 900 times 3, f is going to be equal to 2 ,700, yeah, 2 ,700 newtons.
02:44
And then there is a net force of 75 newtons acting on a girl on a skateboard.
02:49
If her acceleration is 3 meters per second squared, what is her mass? so we have m is going to be equal to f over a.
02:58
So that will be equal to 75 over 3, which equals 25...