ASVAB Mechanical Comprehension Practice Test 448095 Results

Your Results Global Average
Questions 5 5
Correct 0 3.23
Score 0% 65%

Review

1 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 140 lbs. load concentrated at a point 0.5 ft. from the axle?
52% Answer Correctly
22.9
28
350
0
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:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{140 \times 0.5}{2.5} \)
\( F_e = \frac{70.0}{2.5} \)
\( F_e = 28 \)
2

A watt is the unit for which of the following?

71% Answer Correctly

mechanical advantage

power

energy

work
Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.

3

Friction between two or more solid objects that are not moving relative to each other is called:

74% Answer Correctly

gravitational friction

static friction

kinetic friction

dynamic friction
Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.

4

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

61% Answer Correctly

difference in the lengths of the axles

ratio of the diameters of the wheels

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

Coplanar forces:

62% Answer Correctly

have opposite dimensions

act in a common plane

pass through a common point

act along the same line of action
Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.