00:01
For the first problem on the page, we're told there are two objects, object a and object b, where object a has a mass of capital m and is dropped from a height of capital h, while mass b has a mass of half of m and is dropped from a height of twice h.
00:30
And the question is, what is the ratio of the velocity of object a to that of object b? and so to do this, we want to think about conservation of momentum.
00:43
For either ball, they start with some potential energy equal to mgh, and all of that energy will be converted to kinetic energy.
00:55
And so their final energy will be all kinetic and equal to one half.
01:01
Mv squared, which means if we solve for the velocity, the velocity should be equal to the square root of 2gh.
01:10
So if we were then to do this and write up the actual ratio of va to vb, for a, we would have the square root of 2g capital h.
01:24
And for b we would have the square root of 2g to h.
01:31
And so if you then divide both sides of this ratio by the square root of 2g capital h, you would end up with 1 to the square root of 2, which is the same as 1 to 1 .41.
01:50
For the next problem, i'm going to erase all of this to make space for a hit.
01:55
But for the next problem, we are thinking about student a and student b, i believe, walking up a set of stairs...