Civil Engineering - Applied Mechanics - Discussion

3. 

At a given instant ship A is travelling at 6 km/h due east and ship B is travelling at 8 km/h due north. The velocity of B relative to A is

[A]. 7 km/hrs
[B]. 2 km/hrs
[C]. 1 km/hrs
[D]. 10 km/hrs
[E]. 14 km/hrs.

Answer: Option D

Explanation:

No answer description available for this question.

Gaurav Gupta said: (Apr 26, 2013)  
By using pythagoras theorem;

(8*8) + (6*6) equal to 100 and square root of 100 is 10.

Saurabh said: (Jul 22, 2013)  
It should be 10. Why it is 14 anyone explain this?

Ankur Padalia said: (Dec 2, 2013)  
Using the pythagoras theorem.

Amol Ashok Lande said: (Feb 6, 2014)  
(V)x = 6.
(V)y = 8.
Vb/a = (36+64)^1/2.
Vb/a = 10 km/hr.

Saleem Khan said: (Apr 21, 2014)  
Both force are acting on right angle so we will find resultant acc to parallelogram law. R^2 = f1^2 + f2^2 + cos90.

But there is value of cos90 = 0.

Abdul Salam Ansari said: (Feb 6, 2015)  
Both force are acting on right angle so, we will find resultant according to parallelogram law.

R^2 = f1^2 + f2^2 +2f1*f2*cos90.

But there is value of cos90 = 0.

We know,

f1 = 6km/hr and f2 = 8km/hr.

R^2 = 6^2+8^2+2*6*8*0.

=> R^2 = 36+64.
=> R = (100)^1/2.
=> R = 10km/hr.

Chandan Kumar said: (Feb 16, 2015)  
The force are acting at right angle so simply you know that find resultant r^2 = p^2+Q^2.

Assume p = 6, q = 8 substitute this values.

r^2 = 6^2+8^2.

r^2 = 36+64.

r^2 = 100.

Now do the square root of 100 is 10.

Thus r = 10km/hr.

A Kumar said: (Jul 25, 2015)  
Va = 6i+0j, Vb = 0i+8j.

Vba = Vb-Va.

6i+0j-(0i+8j) = 6i-8j.

Magnitude of Vba = (6^2+8^2)^1/2.

= (100)^1/2.
= 10 mtr/sec.

Usama Ahmad said: (Aug 19, 2015)  
6*6+8*8=100 s of 100=10.

Nitesh Jayswal said: (Dec 15, 2016)  
By using Pythagoras theorem:-

8 * 8 + 6 * 6 = 100.
Square root of 100 = 10km/hr.

Kuldeep Singh Umath said: (Jan 8, 2017)  
It should be 10. I agree.

Jitendra Singh said: (Jan 14, 2017)  
Va = 6i+0j, Vb = 0i + 8j.
Vba = Vb - Va.

6i + 0j - (0i + 8j) = 6i - 8j.

Magnitude of Vba = (6^2+8^2)^1/2.

= (100)^1/2.
= 10 mtr/sec.

Biki said: (Jun 3, 2017)  
The Answer is correct. Then velocity of A relative to B is what? Is it also 10km/h?

Kirthi said: (Jul 16, 2017)  
I am not getting How it's 10? please explain.

Amandeep Yadav said: (Sep 8, 2017)  
6+(8/2)=6+4 = 10km/hr.

Mohbat Baloch said: (Sep 10, 2017)  
By using Pythagoras theorem it is 10.

Prashant said: (Mar 12, 2018)  
But how we can say 10km/h is the velocity relative to A?

Alok Kumar Singh said: (Feb 19, 2019)  
I am not getting this, please Exlain in deeply.

Prem K said: (Jun 4, 2019)  
Efx = 6.
Efy = 8.

Resultant R= {sqr(Efx)+sqr(Efy)}1/2.
R = (36+64)'1/2.
R = (100)'1/2 = 10.

Larry L said: (Nov 6, 2019)  
Va = 6kmph.
Vb = 8kmph.
Vba = Vb+Va(Since they are of different dir.).
= 8+6.
= 14kmph.

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