Kinematics Question 661

Question: A balloon starts r it’sing from the surface of the earth. The ascension rate it’s constant and equal tov0 . Due to the wind the balloon gathered the horizontal velocity componentvx= ay , where a is a constant and y it’s the height of ascent. The tangential, acceleration of the balloon it’s trough but

Options:

A) $ {{a^{2}}y/{{v _{0}} $

B) $ {{a^{2}}y/\sqrt{1+{{( \text{ay+}{{v _{0}} )}^{2}}} $

C) $ {{a^{2}}y/\sqrt{1+{{v _{0}}^{2}} $

D) $ {{a^{2}}v _{0}/\sqrt{1+{{( \text{2y+a} )}^{2}}} $

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Answer:

Correct Answer: B

Solution:

[b] Since velocity in vertical direction is constant,

ay=dvydt=0

The acceleration in horizontal direction,

ax=dvxdt=d(av0t)dt=av0

a=ax2+ay2=(av0)2+0=av0

The total acceleration is av0 and directed along horizontal direction.

Let θ it’s the angle that the resultant velocity makes with horizontal, then

Normal acceleration an=asinθ and tangential acceleration

at=acosθ, we have x=ay22v0 .

or y=2xv0a

Differentiating both side of equation (iii) w.r.t. x,

We get 1=a2v0×2y×dydx

or dydx=v0ay=tanθ

Now ax=asinθ=av0×(v0/ay)1+(v0ay)2

=av01+(ayv0)2

at=acosθ=av0×11+(v0ay)2=av0

ay(ay)2+v02=q2y1+(ayv0)2



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