1.Identify a convenient coordinate system for analyzing each of the following situations: a. a dog walking along a sidewalk b. an acrobat walking along a high wire c. a submarine submerging at an angle of 30° to the horizontal

3. a particle with initial velocity v⃗ 0=(5.85×103m/s)j^ enters a region of uniform electric and magnetic fields. the magnetic field in the region is b⃗ =−(1.35t)k^. you can ignore the weight of the particle. a. calculate the magnitude of the electric field in the region if the particle is to pass through undeflected, for a particle of charge +0.640 nc.