Answer:
V=14.9 m/s
Explanation:
In order to solve this problem, we are going to use the formulas of parabolic motion.
The velocity X-component of the ball is given by:

The motion on the X axis is a constant velocity motion so:

The whole trajectory of the ball takes 1.48 seconds
We know that:

Knowing the X and Y components of the velocity, we can calculate its magnitude by:

Answer:

Explanation:
It is given that,
The number of lines per unit length, N = 900 slits per cm
Distance between the formed pattern and the grating, l = 2.3 m
n the first-order spectrum, maxima for two different wavelengths are separated on the screen by 2.98 mm, 
Let d is the slit width of the grating,



For the first wavelength, the position of maxima is given by :

For the other wavelength, the position of maxima is given by :

So,



or

So, the difference between these wavelengths is 14.3 nm. Hence, this is the required solution.
90 F = 43 OR 0.9F = 0.43
(F = 43 / 90 OR 0.43 / 0.9 =) 0.48 N
upwards force = downwards force
(R =) 1.2 N