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A body of mass 5 kg starts from the orig...

A body of mass 5 kg starts from the origin with an initial velocity `vec(u) = 30 hat(i) + 40hat(j) ms^(-1)`. If a constant force `vec(F) = - (hat(i) + 5hat(j))N` acts on the baby , the time in which the y-component of the velocity becomes zero it .

A

5 seconds

B

20 seconds

C

40 seconds

D

80 seconds

Text Solution

Verified by Experts

The correct Answer is:
C
`F = m(dv)/(dt) = 0.15 xx (20)/(0.1) = 30 N` `vec(a) = (vec(F))/(m) = (-(hat(i) + 5hat(j)))/(5)m//s^(2)`
`vec(u) = (30hat(i) + 40hat(j))m//s`
`V_(y) = u_(y) -a_(y) t`
`a_(y) = - hat(j)m//s^(2)`
`u_(m) = 40hat(j) m//s^(2)`
`rArr 0 = 40 - 1 xx t rArr t = 40 Sec`
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