Kinematics 2 Question 1

2. A particle is moving Eastwards with a velocity of 5m/s. In 10s, the velocity changes to 5m/s Northwards. The average acceleration in this time is

(1982, 3M)

(a) zero

(b) 12m/s2 towards North-Eeast

(c) 12m/s2 towards North-West

(d) 12m/s2 towards North

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Answer:

Correct Answer: 2. (b)

Solution:

  1. Given, drag force, F=mψ2

As we know, general equation of force

=ma

Comparing Eqs. (i) and (ii), we get

a=γv2

Net retardation of the ball when thrown vertically upward is

anet=(g+γ2)=dvdtdv(g+γ2)=dt

By integrating both sides of Eq. (iii) in known limits, i.e.

When the ball thrown upward with velocity v0 and then reaches to its zenith, i.e. for maximum height at time t=t,v=0

v00dv(Yv2+g)=0tdt or 1Yv001gY2+v2dv=0tdt1Y1g/Ytan1vg/Y=tv0x2+a2dx=1atan1xa

1γgtan1Yv0g=t



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