Simple Machines：練習問題

In a lever system, what is the name of the fixed point around which the bar rotates?

Which of the following tools is an example of a force-saving (effort-saving) lever where the load is between the fulcrum and the effort?

A worker uses a pulley block system. If the system is designed such that there are \(2\) rope segments supporting the movable pulley, how much effort is theoretically needed to lift a load of \(100\text{ N}\) (ignoring friction and the weight of the pulley)?

In a lever system, what do we call the fixed point that does not move and allows the bar to pivot or rotate?

When two gears are meshed together as shown in a diagram, if the first gear turns in a clockwise direction, in which direction will the second gear turn?

When lifting a heavy load, why is a movable pulley often preferred over a fixed pulley?

A student uses a pair of pliers to cut a wire. Based on the relative positions of the fulcrum, effort, and load, what type of lever is being used and what is its primary mechanical advantage?

A student uses a movable pulley to lift a heavy bucket. If the bucket weighs \(100\text{ N}\), what is the minimum effort force required to lift it (ignoring friction and the weight of the pulley), and how does the distance the effort moves compare to the distance the bucket is raised?

Simple machines are devices that make work easier by changing the magnitude or direction of a force. Study the following three scenarios and answer the questions below.

(a) A worker uses a long wooden plank to push a heavy crate from the ground onto the back of a truck. What is the name of this simple machine, and how does it help the worker? (2 points)
(b) A student is using a fixed pulley to lift a bucket of water. Does this machine reduce the amount of effort needed to lift the bucket? Explain your answer. (2 points)
(c) Many playground slides and wheelchair ramps are examples of a specific simple machine. Explain why making a ramp longer (less steep) makes it easier to move a load to a higher position. (2 points)

Simple machines help us perform work more easily by changing the magnitude or direction of a force.

(a) A pair of scissors is a type of lever. Identify the positions of the fulcrum, effort, and load on a pair of scissors. (3 points)

(b) What class of lever does a pair of scissors belong to, and how is it defined? (2 points)

(c) If a worker uses a single fixed pulley to lift a heavy box, does it reduce the amount of effort needed? What is the primary advantage of using this pulley? (2 points)