A roller-coaster car has a mass of 1070 kg when fully loaded with passengers. As the car passes over the top of a circular hill of radius 22 m, its speed is not changing. (a) At the top of the hill, what is the normal force (using the negative sign for the downward direction) FN on the car from the track if the car's speed is v = 8.4 m/s? (b) What is FN if v = 19 m/s? Use g=9.81 m/s2.

The following statements are about the electroscope. select all that are true. if an electroscope were given a positive charge beforehand, the leaves would move closer together if a positively charged object were brought near. when a properly prepared electroscope is used to determine the type of charge on an object, the total charge on the electroscope changes when the charged object is brought near (but not touching) the electroscope. depending on how the electroscope is prepared beforehand, the leaves can either move together or move apart when negative charge is brought near. an electroscope must first be given a known type of charge before it can be used to identify the types of charges on objects brought near it. when properly prepared, the leaves on an electroscope will always move further apart when negative charge is brought near. the leaves of an electroscope will move apart if it is given either a positive or a negative charge.