请为一位初中生讲解这一道物理题。---**Problem Description:** 如图所示，利用滑轮组从竖井中提升矿石，矿石以0.5 m/s的速度匀速上升，已知矿石重2 700 N，滑轮组的机械效率为90%，不计绳重和摩擦.求: **Questions:** (1)矿石在5s内上升的高度. (2)绳端的拉力. **Chart/Diagram Description:** * **Type:** Pulley system diagram. * **Main Elements:** The diagram shows a pulley system used to lift a load from a vertical shaft. * A fixed pulley is mounted above the shaft opening. * Two movable pulleys are used within the shaft. * A load (represented by a box) is attached to the lower movable pulley. * The rope goes from the pulling end (horizontal to the right), over the fixed pulley, down to the upper movable pulley (attached to the support above), around the upper movable pulley, down to the lower movable pulley (attached to the load), around the lower movable pulley, and the other end is attached to the support near the upper movable pulley. * An arrow indicates the pulling direction of the rope, which is horizontal to the right. * The number of rope segments supporting the load is 3.