If an object is dropped from the top of a building. if it falls 1.2 seconds until it hits the ground, how tall is the building

Let us list out what we know from the question so that we can decide on the appropriate equation.

First, it has been given that the object is 'dropped'.

So, its Initial Velocity   = 0

Acceleration in the vertical direction = 9.8 m/

Time of fall t = 1.2 s

Height of the building h = ?

We see that the best-suited equation is

Plugging in the numbers, we get h = (0)(1.2) + (9.8)

Simplifying the above equation, we get h = 7.056 m

Therefore, the building is 7.1 meters tall.

i think the answer is a, hope this is right, that would be my best guess.

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)