| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.02 |
| Score | 0% | 60% |
Which of the following will increase the mechanical advantage of a second-class lever?
move the object being lifted farther away from the fulcrum |
|
move the fulcrum between the force and the object being lifted |
|
move the object being lifted closer to the fulcrum |
|
decrease the length of the lever |
A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.
Which of the following statements about this pulley configuration is false?
Only multiplies the effort force |
|
This is a block and tackle pulley configuration |
|
Changes the direction of and multiplies the effort force |
|
Mechanical advantage is the number of ropes that support the resistance |
A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.
What type of load varies with time or affects a structure that experiences a high degree of movement?
impact load |
|
dynamic load |
|
concentrated load |
|
static load |
A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.
Which of the following is not a characteristic of a ceramic?
low corrosive action |
|
high melting point |
|
low density |
|
chemically stable |
Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.
Collinear forces:
are unrelated to each other |
|
act in a common plane |
|
pass through a common point |
|
act along the same line of action |
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.