Coulomb's Law Question

1. Charges are placed on the x axis as follows:
q1 = +2µC at x = 0, q2 = -3µC at x = 2m, q3 = -4µC at x = 3m, and q4 = +1µC at x = 3.5m. What is the magnitude and direction of the force on q3?
 

2. A charge q1 = + 4µC (1 µC = 10-6 C) is positioned at the origin. A charge q2 = + 9µC is positioned on the x axis at x = 4m. Where on the x axis can a negative charge q3 be placed so that the force on it is zero? Is there any position off the x axis where the force on q3 will be zero?

Soal Kinematika Gerak Lurus

1.a. Tentukan Kecepatan di titik C!
   b. Tentukan kecepatan di titik B!

2. Sepotong Balok bermassa m meluncur pada suatu talang (lingkaran dalam) seperti terlihat dalam gambar. Jika gaya gesek diabaikan.
a. berapa ketinggian minimum balok yang harus dilepas agar gerakannya dapat mencapai puncak lingkaran (titik B)?
b. Tentukan besar percepatan balok dititik B.