When a particle is projected at an angle to the horizontal, it has range R and time of flight t1. If the same projectile is projected with the same speed at another angle to have the same range and time of flight $t_{2}$ then,

Q. A ball is thrown at angle above horizontal of some height with the some velocity. Time taken for ball to reach first wall and second wall is equal to

T_{1} a n d T_{2}

respectively. Find

T_{1} + T_{2} (T = t i m e o f f l i g h t)

A body is thrown vertically upwards with an initial velocity u. It passes a point at a height h above the ground at time $t_{1}$ while going up and at time $t_{2}$ while falling down. Then the relation between u, $t_{1}$ and $t_{2}$ is

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At time t=0 a small ball is projected from point A with a velocity of 60 m/s at 60∘ angle with horizontal. Neglect atmospheric resistance and determine the two times t1andt2 when the velocity of the ball makes an angle of 45∘ with the horizontal x-axis.

The correct option is C t1=2.19s,t2=8.20sWe have to find the time when the velocity is making an angle of 45 degrees.→u=30^i+30√3^j→a=−10^j→v=→u+→at→v=30^i+30√3^j−10t^j=30^i+(30√3−10t)^jtanθ=30√3−10t30=√3−t/3=±1⇒t=3(√3±1)=8.196s,2.196s

At time t=0 a small ball is projected from point A with a velocity of 60 m/s at $60^{\circ}$ angle with horizontal. Neglect atmospheric resistance and determine the two times $t_{1} a n d t_{2}$ when the velocity of the ball makes an angle of $45^{\circ}$ with the horizontal x-axis.