Question

a projectile can have the same range R for 2 angles of projection . if t1 and t2 be the time of flights in the 2 cases , then t1*t2 is proportional is

Answer 1

Hi malati sen,

 The projectile must have same range when it is complementary i.e   ø and (90 -ø)

  T1= 2usin¤ / g

T2= 2usin ( 90- ¤)/g

 T2 = 2ucos¤/g

Now, T1×T2= 2usin¤/g × 2ucos¤/g

4u² sin¤cos¤/g² 

2u²  2 sin¤ cos¤/g² 

 2/g × u²  2sin ¤/g    ( 2sin¤cos¤ = 2sin¤)

 2/g × R

So T1×T2 is directly  proportional  to Range...

Hope it help u