Many scientific discoveries are made by chance. While studying one phenomenon, a scientist may discover a different one. Such was the case when William Herschel discovered the planet Uranus in 1781. Herschel was charting faint stars in the sky, when he discovered something that was not a star. How can astronomers tell the difference between a star and a planet

Three point charges, two positive and one negative, each having a magnitude of 20 μc are placed at the vertices of an equilateral triangle (30 cm on a side). what is the magnitude of the electrostatic force on the negative charge

Um vetor representa um deslocamento cujo módulo é 20 m. se v faz um ângulo de 60 graus com a horizontal, qual é o valor das componentes horizontal e vertical deste vetor?

In the sport of parasailing, a person is attached to a rope being pulled by a boat while hanging from a parachute-like sail. a rider is towed at a constant speed by a rope that is at an angle of 15 ∘ from horizontal. the tension in the rope is 1900 n. the force of the sail on the rider is 30∘ from horizontal. what is the weight of the rider? express your answer with the appropriate units.