Understanding Simple Machines

What is the main function of a lever in a mechanical system? 杠杆在机械系统中的主要功能是什么？

• To reduce friction

• To change the direction of force

• To increase the speed of movement

• To lift or move heavy objects with less effort

Which of the following is an example of a compound machine? 以下哪项是复合机械的例子？

• Pulley

• Wheel and axle

• Scissors

• Inclined plane

How does a pulley make work easier? 滑轮如何使工作更容易？

• By reducing the weight of the load

• By changing the direction of the force applied

• By increasing the speed of pulling

• By using more energy

Which simple machine consists of a flat surface set at an angle? 哪种简单机械由设置成一定角度的平面组成？

• Wedge

• Screw

• Inclined plane

• Lever

What is a wedge mainly used for in simple machines? 楔子在简单机械中的主要用途是什么？

• To cut or split objects

• To lift objects vertically

• To change the speed of rotation

• To support weight

What happens when two gears of different sizes are combined in a system? 当两个不同尺寸的齿轮组合在一个系统中时，会发生什么？

• The speed remains the same

• The larger gear will turn faster

• The smaller gear will turn faster

• Both gears will stop turning

Which simple machine is an example of a circular lever? 哪种简单机械是圆形杠杆的例子？

• Screw

• Pulley

• Wheel and axle

• Inclined plane

What simple machines are combined to form a screw? 哪些简单机械组合形成了螺丝？

• Lever and pulley

• Inclined plane and wedge

• Wheel and axle

• Pulley and lever

Which simple machine would you use to lift a heavy load straight up? 你会使用哪种简单机械来垂直提升重物？

• Wheel and axle

• Pulley

• Lever

• Wedge

Why are compound machines more effective than simple machines? 为什么复合机械比简单机械更有效？

• They use more electricity

• They combine multiple simple machines to perform complex tasks

• They are made of stronger materials

• They require less effort to build