00:01
All right, so what we have here is a combination of a newton's second law, as well as a one -dimensional kinematics problem.
00:13
But before we get to any intense math, let's translate these english sentences into actual equations by listing the quantities that are given to us to help us figure out what we're supposed to do.
00:27
So the first number that's given to us is the mass of the ice skater, that's 68 .5 kilograms.
00:39
The second number that's given to us is the initial velocity, so we'll call that v0s, and that's equal to 2 .40 meters per second.
00:55
So the third piece of information that's actually given to us in this problem is the final velocity of the ice skater because we're told that he or she comes to rest.
01:07
So they have a final velocity of zero.
01:10
And then the fourth and final piece of information that's given to us is the time interval over which the force is acting.
01:17
So let's call that delta t.
01:19
And that takes 3 .52 seconds.
01:25
Okay, so we are going to indirectly find the force by first finding the acceleration.
01:33
So at the very end of the problem, we're going to apply newton's second law, which is to say that f is equal to ma, force is equal to the product of mass times acceleration...