The length of the track itself is 500m. The vehicles (each of mass 15kg) are dragged along the track back to the top of the ride in stacks of 4. The force required to drag
them at constant speed is 200N
Use an equation from page 2 to calculate the total work done in dragging the stack
back to the start of the ride

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?