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A small particle of mass ` m` is projected at an angle `theta` with the ` x`- axis with an initial velocity ` v_(0)` in the ` x-y `plane as shown in the figure . At a time ` t lt ( v_(0) sin theta)/(g) `, the angular momentum of the particle is where `hat (i) , hat (j) and hat(k)` are unit vectors along `x , y and z` - axis respectively. A. `-mgv_(0)t^(2)costhetahat(j)`B. `mgv_(0)tcosthetahat(k)`C. `-(1)/(2)mgv_(0)t^(2)costhetahat(k)`D. `(1)/(2)mgv_(0)t^(2)costhetahat(i)` |
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Answer» Correct Answer - 3 `vec(L)=vec(r)xx(m vec(v))` `vec(r)=v_(0)cos thetat hat(i)+(v_(0)sinthetat-(1)/(2)g t^(2))hat(j)` `vec(v)=v_(0)cos theta hat(i)+(v_(0)sintheta-g t)hat(j)` `vec(L)=mv_(0)costhetat(-(1)/(2)g t)hat(k)` `=-(1)/(2)mg v_(0) t^(2) costheta hat(k)` |
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