A girl standing on a floor would have two opposite forces acting on it. These forces are the weight and the normal force. Since no other forces are acting and that the girl is at rest, then the weight must equate to the normal force. Therefore, the supporting force would be:
F = mg = 55kg (9.81 m/s^2) = 539.55 N
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:
B. blocks 2 & 3.
Explanation:
Block 1 has equal & opposite forces acting on it.
Block 2 has 5N on one side, 3N on the other. It will move in the direction the 5N of force is pushing.
Block 3 has no opposing force.
1 meter = 1e9 nm
To get meters, divide nanometers by 1e9: 9.95nm / 1x10^9 = 9.95x10^-9 meters
Answer: 9.95e-9 meters
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