Bennett Mechanical Test Pulleys and Levers 3

Question 1

A pair of scissors is an example of which combination of simple machines?

Accepted Answer

Two first-class levers

Answer

Scissors combine two first-class levers pivoting around a central fulcrum.

Question 2

Which lever class always produces a mechanical advantage less than 1?

Accepted Answer

Third-class lever

Answer

In a third-class lever the effort arm is shorter than the load arm, giving a mechanical advantage below 1 but more speed.

Question 3

Two pulleys are arranged so one is fixed and one is movable. What is the mechanical advantage?

Accepted Answer

2

Answer

One fixed plus one movable pulley gives a mechanical advantage of 2 from two supporting rope segments.

Question 4

On a balanced seesaw, a 100 lb child sits 3 ft from the pivot. Where must a 60 lb child sit to balance it?

Accepted Answer

5 ft from the pivot

Answer

Balance requires equal moments: 100 × 3 = 300, so 300 ÷ 60 = 5 ft.

Question 5

A bottle opener that pivots against the cap edge is which class of lever?

Accepted Answer

Second-class lever

Answer

A bottle opener has the load (cap) between the fulcrum and the effort, making it a second-class lever.

Bennett Mechanical Test Practice Test