Question

1. The screens of cathode ray tubes in CRT television sets and oscilloscopes emit light when they are struck by rapidly moving electrons. Electrical deflecting plates are used to control where the electrons strike. In the figure, electron with an initial horizontal velocity of 2 x 107 m/s experience a vertical acceleration of 1.2 x 1014 m/s while they are between the plates, which are 0.2 m long. (a) How long will the electrons be between the plates? (b) In what direction will they be moving after they leave the plates? Express your answer in unit vector notation and as a velocity vector with angle 8. (c) If the screen is 0.18 m from the end of the plate, where will the electron strike the screen? Assume that if there is no vertical acceleration, the electrons will strike at (0,0). (d) What vertical acceleration is necessary if they are to strike the screen at (0,-0.25)? 1.2 x 101m/s? = 2 x 10 m/s 02 2. Show that the maximum range for an object launched at a given speed from below its landing point occurs for a launch angle greater than 45º 3. A flea can jump 0.03 m with a takeoff angle of 70°. (a) What is the fleas initial velocity? (b) If the flea achieves this velocity in a takeoff distance of 8 x 10m acceleration during takeoff? , what is its average 4. A partide moves horizontally in uniform circular motion, over a horizontal ry plane at constant speed. At t = 4.00 s, it is at point (4.00 m, 5.00 m) with velocity (3.00 m/s) and acceleration in the positive r direction. At time to = 10.00 s, it has velocity (-3.00 m/s) i and acceleration in the positive y direction. What are the 2, y) coordinates of the center of the circular path if t2-t is less than one period?

Answer 1

solution 7 t = 7 - t = 0.2 2X107 to X100 Arruer ditplacement etery velocity along X-aks Vm = 200x107 mis aleny Y-directia after t= 100 sec Vy = at y = 1.2x10l4 x 100 Vg = 412 4100 m/s tomo = - tmo - Elite ) tamo =(-0.6810) timo =-0.06 0 =-3.43°) Arius

vertical displacement of electron 9,- -4at? 9= -4 412 80014 x 10-16 9,= -0.68102 19,=-6410-?malong nag.ahiwe y-direction This is After this lixplacement when electron Coming out of plate Lef electron sprike plate at tat t = lottot 2x107 t = o.ogx10-7 It. 941019 sec displacement of electron along -y-direction in t'a g+10mg see Y₂ = -9x105 X 1-2 Xrolt-d Y = -9410-9 x 124100 Y = -10.8x16"> % 94, 9 19 = 16.0 x103 m

Ang ☺ @ election will shibe at (0, 16:0x103). To Atribe electron at (0, -0.25). y = fat? + @ H) #' wthe y = 0.25 m t= 1000 sec t = 9x109 sec Patting valus 0.25 = txaxio-16 + axloof gx10g 0.25 = A + oiga) xroto 1.4a= 0.25x106 la = 1.78X1015 misal Anur