The mirror formula for curved mirrors is:

where
f is the focal length of the mirror

is the distance of the object from the mirror

is the distance of the image from the mirror
The sign convention that should be used in order to find the correct values is the following:
-

: positive if the mirror is concave, negative if the mirror is convex
-

: positive if the image is real (located on the same side of the object), negative if it is virtual (located on the opposite side of the mirror)
Answer: F = ma,
Explanation:
the most famous equation in physics, establishing an equivalence between energy and mass. But is this the most important equation in physics? Knowledgeable scientists will tell you no. The most important equation in physics is F = ma, also known as Newton's second law of mechanics.
Of the list, Ultraviolet waves have the shortest wavelength
Solution :
Given
Diameter of the roulette ball = 30 cm
The speed ball spun at the beginning = 150 rpm
The speed of the ball during a period of 5 seconds = 60 rpm
Therefore, change of speed in 5 seconds = 150 - 60
= 90 rpm
Therefore,
90 revolutions in 1 minute
or In 1 minute the ball revolves 90 times
i.e. 1 min = 90 rev
60 sec = 90 rev
1 sec = 90/ 60 rec
5 sec = 
= 75 rev
Therefore, the ball made 75 revolutions during the 5 seconds.