ASVAB Mechanical Comprehension Practice Test 138473 Results

Your Results Global Average
Questions 5 5
Correct 0 2.84
Score 0% 57%

Review

1 If the handles of a wheelbarrow are 2.0 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 160 lbs. load concentrated at a point 0.5 ft. from the axle?
52% Answer Correctly
None of these is correct
24
40
320

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:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{160 \times 0.5}{2.0} \)
\( F_e = \frac{80.0}{2.0} \)
\( F_e = 40 \)

2

The work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. This defines which of the following?

61% Answer Correctly

Pascal's law

conservation of mechanical energy

mechanical advantage

work-energy theorem


Solution

The work-energy theorem states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. Simply put, work imparts kinetic energy to the matter upon which the work is being done.


3

What type of load doesn't create specific stress points or vary with time?

60% Answer Correctly

static uniformly distributed load

impact load

non-uniformly distributed 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.


4

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

ratio of the diameters of the wheels

difference in the lengths of the axles

length of the axle

difference in the diameters of the wheels


Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.


5

A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?

50% Answer Correctly

in the middle

near the car

near the truck

tension is equal in all parts of the rope


Solution

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.