Field Theory Answers

Find force on electron if magnitude is 40

On a 200 km bike cycle ride, you ride the first 90 km at an average speed of 20 m/s. What must your average speed over the next 40 km be to have your average speed for the total 200 km be?

 (a)  60 m/s?

 (b) Given this average speed for the first 90 km, can you possibly attain an average speed of

    80 m/s for the total 200 km ride? Explain.

Please reply as fast as possible

An electron in a uniform electric and magnetic field has a velocity of 1.20  104 m/s (in the positive x direction) and an acceleration of 2.00  1012 m/s2 (in the positive z direction). If the electric field has a magnitude of 20.0 N/C (in the positive z direction), what can you determine about the magnetic field in the region? What can you not determine

. An electron is accelerated through 2 400 V from rest and then enters a uniform 1.70-T magnetic field. What are (a) the maximum and (b) the minimum values of the magnetic force this particle can experience? 

On a 200 km bike cycle ride, you ride the first 90 km at an average speed of 20m/s. What must your average speed over the next 40 km to be have your average speed for the total 200 km be?

a. 60m/s.

b. Given this average speed for the first 90 km, can you possibly attain an average speed of 80 m/s for the total 200 km ride? Explain.

Given three vectors A = 24i + 33j, B = 55i - 12j and C = 2i + 43j

 (a) Find the magnitude of each vector.

 (b) Write an expression for the vector difference A - C.

 (c) Find the magnitude and direction of the vector difference A-B.

 (d) In a vector diagram show vector A + B, and A - B, and also show that your diagram agrees 

A person is riding on a flatcar traveling at a constant speed of 200 km/s (Fig.). He wishes to throw

a ball through a stationary hoop 90 km above the height of his hands in such a manner that the ball

will move horizontally as it passes through the hoop. He throws the ball with a speed of 250 m/s

with

respect to himself,

(a) How many time required after he releases the ball will it pass through the hoop?

(b) What must the vertical component of the initial velocity of the ball?

(c) At what horizontal distance in front of the hoop must he release the ball?

(d) When the ball leaves the man's hands, what is the direction of its velocity relative to the

frame of reference of the flatcar? Relative to the frame of reference of an observer standing

on the ground?

90 km

V

V

X

v = 200 km/s

A driver at Dewaan Motors is testing a new model car with a speedometer calibrated to read m/s

rather than km/h. The following series of speedometer readings was obtained during a test run

along a long, straight road:

Time (s)

Speed (m/s)

0 1 3 5 7 9

0 0 4 7 10 13

15

17

19

11 13

17 22

23

26

29

(a) Compute the average acceleration during each 2-s interval. Is the acceleration constant? Is it

constant during any part of the test run?

(b) Make a (v-t) graph of the data, using scales of 1cm = 1s horizontally and 1cm = 2m/s

vertically. Draw a smooth curve through the plotted points. By measuring the slope of your

curve, find the instantaneous acceleration at t = 6 s, 18 s, and 25 s.

i.                   For transverse waves on a string, is the wave speed the same as the speed of any part of the string? Explain the difference between these two speeds. Which one is constant? Which has a more direct influence on the loudness of a sound wave: the displacement amplitude or the pressure amplitude? Explain your reasoning.

ii.                 A sound source and a listener are both at rest on the earth, but a strong wind is blowing front the source toward the listener. Is there a Doppler effect? Why or why not?

iii.               When you use a hand pump to inflate the tires of your bicycle, the pump gets warm after a while. Why? What happens to the temperature of the air in the pump as you compress it? Why does this happen? When you raise the pump handle to draw outside air into the pump, what happens to the temperature of the air taken in? Again, why does this happen?

iv.               Suppose the two plates of a capacitor have different areas. When the capacitor is charged by connecting it to a battery. do the charges on the two plates have equal magnitude. Or may they be different? Explain your reasoning.

You connect a number of identical light bulbs to a flashlight battery. (a) What happens to the brightness of each bulb as more and more bulbs are added to the circuit if you connect them (i) in series and (ii) in parallel? (b) Will the battery last longer if the bulbs are in series or in parallel? Explain your reasoning