Bennett Mechanical Test Pulleys and Levers 4

Question 1

A crowbar used to pry up a board with the curved end resting on the ground is which lever class?

Accepted Answer

First-class lever

Answer

A prying crowbar has the fulcrum between the effort and the load, making it a first-class lever.

Question 2

A movable pulley system reduces the lifting force to one-third. How many rope segments support the load?

Accepted Answer

3

Answer

Reducing force to one-third means a mechanical advantage of 3, which equals 3 supporting rope segments.

Question 3

Using a 6 ft lever with the fulcrum 1 ft from the load, what is the maximum mechanical advantage?

Accepted Answer

5

Answer

Effort arm is 5 ft and load arm is 1 ft, so mechanical advantage is 5 ÷ 1 = 5.

Question 4

A pair of tweezers used to grip a small object is which lever class?

Accepted Answer

Third-class lever

Answer

Tweezers are third-class levers because the effort is applied between the fulcrum and the load.

Question 5

Why does a single fixed pulley have a mechanical advantage of 1?

Accepted Answer

Only one rope segment supports the load

Answer

A fixed pulley has just one rope segment supporting the load, so it offers no force multiplication.

Bennett Mechanical Test Practice Test