00:01
The springs natural length is 15 centimeters and a force of 30 newtons required to stretch it to 40 centimeters.
00:06
So what is the stretch? the stretch is from 40 minus 15, right? so that will be 25 centimeters.
00:17
And what is force by the way? the force is same as kx, kx not where x not is the stretch in this case.
00:23
So force is 30 and k is unknown.
00:27
And remember that we have to keep x not and meat.
00:30
So that will be 0 .25 meters.
00:32
So we write 0 .25 over here.
00:36
We divide both sides by 0 .25 to get 120 as the value of k.
00:41
Now we have to find out how much work is done in stretching it from 20 to 50.
00:46
So 20 to 50 means the first elongation x1 will be 20 minus 15, right? it's natural lens is 15, which is 5.
00:54
And the second one is 50 minus 15, which is 35.
00:58
These are in centimeters.
00:59
So we will have 0 .05 over here.
01:03
X1 as 0 .05 over here...