A girl throws a ball vertically upwards. It takes a time of 3.20 s to return to her hand. Assume air resistance is negligible.
What is the initial speed with which the ball is thrown?

15.68ms

Explanation:

From the question, we are informed that it takes a time of 3.20s for the ball to return to her hand.

Then, the time thst will be taken by the ball to reach maximum height will be 1.6s

Let the initial speed be represented by v.

Therefore,

Vf = v - gt

where,

g = 9.8

t = 1.6

Vf = v - gt

0 = v - (9.8 × 1.6)

0 = v - 15.68

v = 15.68ms

=v−gt

⟹0=v−9.8×1.6

⟹v=15.68ms

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.