What do the positive helium ions do for the e / m apparatus? choose the most complete, best answer.

a. they are there only when the electrons are not orbiting, otherwise, they move to the outer edge of the bulb.

b. they are there so that the bulb does not implode.

c. they emit photons which allow the beam to be seen.

d. they get hot and glow.

e. they focus the electron beam.

f. they focus the electron beam and they emit photons which allow the beam to be seen.

2. when is a charge acted upon by a magnetic force?

1.in one challenge on the titan games, competitors have to lift 200 pounds up a long ramp. angel is able to move the weight in 42 seconds. anthony gets it done in only 38 seconds. which statement is true? angel has more power than anthony. angel does more work than anthony. anthony does more work than angel. anthony has more power than angel. 2.a mountain climber exerts 41,000 j of work to climb a cliff. how much power does the climber need if she wants to finish in only 500 seconds? power = work / time 20,500,000 watts 82 watts 0.0122 watts 41,500 watts 3.your family is moving to a new apartment. while lifting a box 83 joules of work is done to put the box on a truck, you exert an upward force of 75 n for 3 s. how much power is required to do this? (hint: you only need two of the 3 numbers given! ) power = work / time 249 watts 25 watts 2075 watts 27.7 watts

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?