Engineering Mechanics - Force Vectors - Discussion
Discussion Forum : Force Vectors - General Questions (Q.No. 1)
1.
The cord is attached between two walls. If it is 8 m long, determine the distance x to the point of attachment at B.
Discussion:
13 comments Page 1 of 2.
Mr. Right said:
1 decade ago
The answer is actually 7.68.
The diagram is not a right triangle, as it is in 3 dimensions and not on an x,y axis.
Correct approach:
A=0i+1j+4z.
B=?i+0j+2z.
Distance between 2 points in 3d:
sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2).
(x-0)^2 + (0-1)^2 + (2-4)^2.
x^2 + 1 + 4 = 8^2.
x^2=59.
x= sqrt59 = 7.68115.
Now if you check that you will see that it is correct, as opposed to the answer that you all tried to simplify and didn't bother to check your work.
The diagram is not a right triangle, as it is in 3 dimensions and not on an x,y axis.
Correct approach:
A=0i+1j+4z.
B=?i+0j+2z.
Distance between 2 points in 3d:
sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2).
(x-0)^2 + (0-1)^2 + (2-4)^2.
x^2 + 1 + 4 = 8^2.
x^2=59.
x= sqrt59 = 7.68115.
Now if you check that you will see that it is correct, as opposed to the answer that you all tried to simplify and didn't bother to check your work.
ABDUL KHALEQAUE said:
10 years ago
Suppose B point at black wall and A point at white wall. Draw a line perpendicular to white wall. Now apply Pythagoras formula. You will find square root of (8^2-(4-2)^2) = 7.7459.
It will give you hypotenuse of new triangle. Again apply same formula square root of (7.7459^2-1^2) = 7.68.
It will give you hypotenuse of new triangle. Again apply same formula square root of (7.7459^2-1^2) = 7.68.
(1)
Second Right said:
1 decade ago
I agree with Mr. Right, there are two perpendicular right triangles that you must solve. This is an engineering mechanics question, not a grade 10 trigonometry question. The answer is x=sqrt(59).
Woxiiii said:
10 years ago
It's 3D Pythagoras so all you have to do is substitute into the formula a^2+b^2+c^2=d^2.
(1)
Jay aswani said:
1 decade ago
Sir please provide complete solution so that we can take advantage of that.
Riyaz Ibrahim said:
10 years ago
I am not satisfied, try to solve in simple format.
Karthi said:
10 years ago
Sir I cannot understand so please explain.
(1)
D.Vengadesan said:
1 decade ago
Sir I want explanation for this answer.
Prahlad said:
8 years ago
2^2-8^2-1^2=59 ,
Then √59=7.68.
Then √59=7.68.
Kunal said:
7 years ago
8^2=1^2+2^2+x^2.
x^2=59,
x = 7.68,
x^2=59,
x = 7.68,
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