Answer:
After 9 seconds the object reaches ground.
Step-by-step explanation:
We equation of motion given as h = -16t²+128t+144,
We need to find in how many seconds will the object hit the ground,
That is we need to find time when h = 0
0 = -16t²+128t+144
16t²-128t-144= 0

Negative time is not possible, hence after 9 seconds the object reaches ground.
0.304 cm I think - let me check
The correct answer is: wavelength =
4562 nm
Explanation:Rydberg's formula is given as:
![\frac{1}{\lambda} = R[ \frac{1}{n_1^2} - \frac{1}{n_2^2} ]](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B%5Clambda%7D%20%3D%20R%5B%20%5Cfrac%7B1%7D%7Bn_1%5E2%7D%20%20-%20%5Cfrac%7B1%7D%7Bn_2%5E2%7D%20%5D%20)
--- (1)
Where
R = Rydberg's constant = 1.096 * 10^7 per meter

= 5

= 7
λ = Wavelength
Plug in the values in (1):
(1)=>
![\frac{1}{\lambda} = (1.096 * 10^7)[ \frac{1}{5^2} - \frac{1}{7^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%7D%20%3D%20%281.096%20%2A%2010%5E7%29%5B%20%5Cfrac%7B1%7D%7B5%5E2%7D%20-%20%5Cfrac%7B1%7D%7B7%5E2%7D%20%5D)