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.
Answer:
Final velocity, V = 11.5m/s
Explanation:
Given the following data;
Initial velocity, U = 2.5m/s
Acceleration, a = 1.5m/s²
Time, t = 6secs
To find the final velocity, we would use the first equation of motion
V = U + at
Substituting into the equation, we have
V = 2.5 + 1.5*6
V = 2.5 + 9
Final velocity, V = 11.5m/s
Use the eq. of Young modulus Y=(F/A)/(∆l/lo)
dimana ∆l is the elongation of wire, lo is its initial length.
So ∆l = (F/A)lo/Y.
∆l = (1000N/(6.5 × 10^-7 m^2))×(2.5m)/(2.0 × 10^-11 N/m^2)
Use calculator to finish it.