00:01
We're going to be looking at problem 24 of chapter 5 of the physics fifth book.
00:06
The question says, a 12 kilogram block of steel is at rest on a horizontal table.
00:12
The coefficient of static friction between the block and the table is 0 .52.
00:17
For part a, what is the magnitude of the horizontal force that will start the block moving? for part b, what is the magnitude of the force acting upwards, 62 degrees from the horizontal that will start the block moving? and for c, if the force acts down to 62 degrees from the horizontal, how large, can it be without causing the block to move? so this diagram is for all parts, so i'll go through it individually for each part.
00:40
So for part a, it asks us, what is the magnitude of the horizontal force that will cause the block to move? so this is our pretty simple setup.
00:48
We've got our weight here, w equals mg, we've got our normal force n, we've got our friction going to the left, and we've got our force going to the right.
01:00
So therefore, we can calculate our fmin to be equal to the friction, which is 0 .52 times 12 times 9 .8, and that equals 61 newton.
01:14
2 signatures figures.
01:17
For part b, it asks us to calculate the magnitude of the force upwards 62 degrees from the horizontal that will start the block moving...