A roller coasters velocity at the top of the hill is 7 m/s. 2 seconds later it reaches the bottom of the hill with a velocity of 15 m/s. What is the
acceleration of the coaster

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it

dang that balls went far

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.