Abasketball is thrown straight up into the air and takes 2.5 seconds to reach the top of it's arc. the acceleration due to gravity is 9.8m/s ^2 downwards. what was the initial velocity of the ball?

Let say the basket ball is tossed upwards with initial speed "v"

now when it moves up in the air its speed will decrease due to acceleration of gravity in opposite direction

So here we can say that its final speed at the top position will be zero

here it will take t = 2.5 s to reach the top

now we can use equation of kinematics

now we have

so the ball is tossed up initially with speed 24.5 m/s

here we know that ball will drop down by total distance 3.2 m

so here we know that

now using kinematics

now in the same time it will cover horizontal distance of 0.75 m

so speed of the ball will be

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.