Hiaaa I need help pwease" concerning the planetary orbits why was Copernicus somewhat inaccurate?"

Act has a 1200: 5 or 240: 1 turns ratio. it is short circuited. what is the maximum current at 1200a primary if we put a 100ohm resistor across the secondary end of the ct. use it as current source circuit.

When a 5.0kg cart undergoes a 2.2m/s increase in speed, what is the impulse of the cart

The boy of mass 30 kg is at r1= 2 meters from the fulcrum. of the girl is 45 kg, at what r2 must she sit so that they are balanced ?