1. Proton
2. negative ion
3. electric charge
4. electron
5. repel
6. attract
7. positive ion
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.
The 120 decibel sound has more amplitude than the 100 decibel sound.
In Physics, the relation between amplitude and intensity is that the intensity of the wave is directly proportional to the square of its amplitude.
So 10 gallons of gas would let you travel 300 Miles.
x gallons = 50 Miles
10 : 300 :: x : 50
x = 500/300
x = 1.66667 gallons.
So, the car would run 10 - 1.6666 gallons = 8.33 gallons.
After that, the warning light turns ON!
Hope this helps!!