The elements that are considered very reactive are part of which family

Astudent wears sunglasses to her read a book more easily which wave interaction occurs as light passes from the air into the plastic lenses? a polarization b.refraction c.diffraction d. interference

Aplayground slide is 8.80 ft long and makes an angle of 25.0° with the horizontal. a 63.0-kg child, initially at the top, slides all the way down to the bottom of the slide. (a) choosing the bottom of the slide as the reference configuration, what is the system's potential energy when the child is at the top and at the bottom of the slide? what is the change in potential energy as the child slides from the top to the bottom of the slide? (include the sign of the value in your answer.)

Ajoint produces movement when its angle decreases. which type of movement is it?