(Choose all the answers that apply.) Stars:

1. generate their own energy
2. use their own matter to create nuclear reactions
3. are classified primarily by temperature
4. usually seem bright if they are close to Earth
5. are terrestrial bodies
(i don't know how the point thing works so 50 points is up for grabs)

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s