Anybody else failing school i'm doing virtual

If element x has 99 protons how many electrons does it have

Asled is being held at rest on a slope that makes an angle θ with the horizontal. after the sled is released, it slidesa distance d1 down the slope and then covers the distance d2 alongthe horizontal terrain before stopping. find the coefficient ofkinetic friction μk between the sled and the ground, assumingthat it is constant throughout the trip. find the coefficient of kinetic frictionμk. express your answer in terms of someor all of the variables d1, d2, and θ.

Aflute player hears four beats per second when she compares her note to a 523 hz tuning fork (the note c). she can match the frequency of the tuning fork by pulling out the “tuning join” to lengthen her flute slightly. what was her initial frequency?