ASVAB Mechanical Comprehension Practice Test 823469 Results

Your Results Global Average
Questions 5 5
Correct 0 3.00
Score 0% 60%

Review

1

The mechanical advantage of a block and tackle is equal to which of the following?

69% Answer Correctly

the number of input forces

the number of connecting ropes

the number of pulleys

the number of loads
Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement.  So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

2

What type of load varies with time or affects a structure that experiences a high degree of movement?

66% Answer Correctly

dynamic load

impact load

static load

concentrated load
Solution

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.

3 If the handles of a wheelbarrow are 2.5 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 150 lbs. load concentrated at a point 1.0 ft. from the axle?
52% Answer Correctly
-15.9
60
33
None of these is correct
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{150 \times 1.0}{2.5} \)
\( F_e = \frac{150.0}{2.5} \)
\( F_e = 60 \)
4

For any given surface, the coefficient of static friction is ___________ the coefficient of kinetic friction.

54% Answer Correctly

equal to

lower than

higher than

opposite
Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).

5

A box is resting on a smooth floor. Static friction is present:

59% Answer Correctly

when an attempt is made to move the box

only if normal force is present

if the coefficient of friction is greater than one

at all times
Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).