Keyboard of basics piano pls help

Apulley system is used to lift a 2,000 newton engine up a distance of 3 meters. the operator must apply a force of 250 newtons to the chain of the pulley system to lift the motor. to lift the engine 3 meters, the operator must pull a total of 30 meters of chain through the pulley system. what is the value of di?

Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise. to get some idea of the size of this effect, calculate the change in length of a column of water 1.00 km high for a temperature increase of 1.00ºc. note that this calculation is only approximate because ocean warming is not uniform with depth. (answer in ×10^{-3} −3 m)

Asmall 12.00g plastic ball is suspended by a string in a uniform, horizontal electric field with a magnitude of 10^3 n/c. if the ball is in equilibrium when the string makes a 30 ° angle with the vertical, what is the net charge on the ball?