The magnitude of an object's charge can either increase or decrease the attraction/ repulsion between another object. The larger the difference of the two object's charges, the stronger opposite charges attract, and the stronger like charges repel.
Physical erosion is the process where rocks change their physical properties with out changing there basic chemical components. :8)
At the bottom of the circle, the ball is being pulled upward by tension in the rope and downward by its own weight, so that the net force on it is
∑ F = 450 N - (0.75 kg) g = (0.75 kg) a
where a is centripetal acceleration. At this maximum tension, the ball has a maximum centripetal acceleration of
a = (450 N - (0.75 kg) g) / (0.75 kg) = 590.2 m/s²
Then its maximum tangential speed v is such that
a = v² / (1.0 m)
⇒ v = √((1.0 m) a) ≈ 25 m/s
