An ideal pendulum is often discussed when studying simple harmonic motion.

what are the conditions needed for an ideal pendulum? check all that apply.

gravitational force acts to pull the pendulum’s mass down.
the mass of the rod of the pendulum is evenly distributed along the rod.
the pivot on which the pendulum swings is frictionless.
the pendulum swings through its equilibrium position as a result of inertia.
tension acts downward on the pendulum’s mass.

Astudent creates a model of a closed ecosystem by filling a glass tank half full with water, then adding 10 snails and two small aquatic plants. the next day, all the snails are dead. what is the most likely cause of their death?

While studying chemical reactions and conservation of matter, sarah's class conducted a variety of experiments. sarah and her lab partner found the mass of a wax candle and placed the candle in a flask. the students lit the candle and let it burn to completion. all that was left was wax and charred candle wick. per their teacher's instructions, the students found the mass of the products. their data can be seen in the data table. formulate a hypothesis the students could test to explain why the experiment did not support the law of conservation of matter. a) the students could repeat the experiment using different candles; there might have been a flaw in the candle. b) the experiment should be repeatable. the students should run several trials and then take an average of the after mass in each trial. c) the students should have someone in the class check their measurement skills as they repeat the experiment. they may have made an error using the balance. d) the students should burn the candle in a container that has some type of lid so that any gas that is a product of the reaction can be contained and massed. submit

Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?