1.

(b) A projectile with initial speed u, can have the same range R for two angles ofprojection. If t1 and t2 be the time of flight in the two cases, then find the value ofT1T2 in terms of R

Answer»

Answer:

GIVEN:

A PROJECTILE with speed U , has same range R , for 2 different time period.

To find:

t1 × t2 = ? (in terms of R)

Calculation:

For constant Projection velocity and same range , this condition is only possible only when a Projectile has been thrown at complementary angles.

Let one angle be θ and the

other be (90 - θ).

Calculation:

Time for 1st Projection be t1

t1 =  \dfrac{2u \sin( \theta) }{g}

Time for 2nd Projection be t2

t2 =  \dfrac{2u \sin(90 \degree -  \theta) }{g}

=  > t2 =  \dfrac{2u \cos( \theta) }{g}

Now as per QUESTION :

\therefore \: t1 \times t2

=  >   \dfrac{2u \sin( \theta) }{g}  \times \dfrac{2u \cos( \theta) }{g}  \:

=  > ( \dfrac{2}{g})  \times  \dfrac{ {u}^{2}  \times 2 \sin( \theta) \cos( \theta)  }{g}

=  > ( \dfrac{2}{g} ) \times  \dfrac{ {u}^{2} \times  \sin(2 \theta)  }{g}

=  >  \dfrac{2R}{g}

So final answer is:

\boxed{ \large{ \red{t1 \times t2 =  \frac{2R}{g}}}}



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