Question

5. Haley throws her ball downward with speed v from height 2h. Simultaneously, Joe drops his ball from rest at height h. What should v be so that the two balls hit the ground at the same time

Answer 1

Answer:

We know that the second equation of motion is

S= ut + 1/2a²

And S is displacement and u is initial velocity

So in the case of Haley lets take downwards as positive Y-axis

S = 2h and

initial velocity = v

a = g (acceleration due to gravity = 9.8)

Substituting

2h = vt + 1/2gt²

And for Joe we take ownwards as positive Y-axis

S = h and

initial velocity = 0 (since the ball is dropped from rest)

a = g

h = 0x t + 1/2gt2²

t2= √ 2h/g

Now since both balls reach ground at same time: t1=t2

So

putting value of t2 in Hayley's equation:

2h= v(√2h/g) + 1/2 g( √2h/g)²

So v= √gh/2