Answer:
Step-by-step explanation:
3. Short Answers:
a. A lever is a simple machine consisting of a rigid bar or rod that rotates around a fixed point called a fulcrum.
b. A second-class lever has the effort in the middle.
c. A first-class lever cannot change the direction of the applied effort.
d. A third-class lever cannot do work faster.
e. The mechanical advantage of a lever is the ratio of the output force to the input force.
f. The formula relating mechanical advantage (MA), velocity ratio (VR), and efficiency is: efficiency = (MA / VR) * 100.
g. The value of efficiency is always less than 100% because some energy is lost due to friction, heat, and other factors during the operation of the lever.
4. Detailed Answer:
A lever is a simple machine that helps amplify or redirect a force. It consists of a rigid beam or rod that is capable of rotating around a fixed point called a fulcrum. The fulcrum acts as a pivot point for the lever to move.
There are three types of levers: first-class, second-class, and third-class levers. In a first-class lever, the fulcrum is located between the effort and the load. Examples of first-class levers include a seesaw or a pair of scissors. This type of lever can change the direction of the applied effort.
In a second-class lever, the load is located between the fulcrum and the effort. An example of a second-class lever is a wheelbarrow. The effort is applied on one end, the load is at the other end, and the fulcrum is in the middle. Second-class levers provide a mechanical advantage, making it easier to lift heavy loads.
In a third-class lever, the effort is applied between the fulcrum and the load. Examples of third-class levers are tweezers or a baseball bat. Third-class levers do not provide a mechanical advantage, meaning that the effort force is greater than the load force. However, they allow for greater speed and range of motion.
The mechanical advantage of a lever is the ratio of the output force (load) to the input force (effort). It is a measure of how much the lever amplifies or reduces the force applied. A lever with a mechanical advantage greater than 1 amplifies the force, while a lever with a mechanical advantage less than 1 reduces the force required.
The formula relating mechanical advantage (MA), velocity ratio (VR), and efficiency is given by efficiency = (MA / VR) * 100. Efficiency represents the effectiveness of the lever in converting input force to output force. It is always less than 100% because some energy is lost due to factors like friction, heat, and other inefficiencies in the lever's operation.