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Water flows though a pipe with a velocity given by V→ = 
4 + x + y 
ĵ m/s t
m/s, where ĵ is the unit vector in the y direction, t(>0) is in seconds, and x and y are in meters. The magnitude of total acceleration at the point (x, y) = (1, 1) at t = 2 s is _____ m/s².
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- 3 m/s²
- 29 m/s²
- 10 m/s²
- 30 m/s²
Correct Option: A
Given:
| V = | ![]() | + x + y | ![]() | ĵ m/s | |
| t |
V = uî + vĵ + wk̂
u = 0, w = 0
| V = | ![]() | + x + y | ![]() | ĵ | |
| t |
a = axî + ayĵ + azk̂
| ax = u | + v | + w | + | = 0 | ||||
| ∂x | ∂y | ∂z | ∂t |
| az = u | + v | + w | + | ||||
| ∂x | ∂y | ∂z | ∂t |
| ay = u | + v | + w | + | ||||
| ∂x | ∂y | ∂z | ∂t |
| = u | + v | ||
| ∂y | ∂t |
| = | ![]() | + x + y | ![]() | × 1 + | ![]() | ![]() | ||
| t | t² |
| ay = | ![]() | + x + y − | ![]() | ĵ | ||
| t | t² |
Now, At (x,y) = 1,1 and t = 2 sec.
Total acceleration is given by,
| a = ay = | ![]() | + 1 + 1 − | ![]() | = 3 m/s² | ||
| 2 | 4 |