Question

Two spherical balls having equal masses with radius of $5cm$ each are thrown upwards along the same vertical direction at an interval of $3s$ with the same initial velocity of $35m/s$, then these balls collide at a height of ______$m$.
(Take $g=10m/s^2$ )

Answer 1

Answer: 50

When both balls will collied
$Y_1=Y_2$
$35t-\frac{1}{2}\times 10\times t^2=35(t-3)-\frac{1}{2}\times 10\times (t-3{)}^2$
$35t-\frac{1}{2}\times 10\times t^2=35t-105-\frac{1}{2}\times 10\times t^2$
$-\frac{1}{2}\times 10\times 3^2+\frac{1}{2}\times 10\times 6t$
$0=150-30t$
$t=5\sec$
$\therefore$ Height at which both balls will collied
$h=35t-\frac{1}{2}\times 10\times t^2$
$=35\times 5-\frac{1}{2}\times 10\times 5^2$
$h=50m$