ASVAB Mechanical Comprehension Practice Test 511133 Results

Your Results Global Average
Questions 5 5
Correct 0 3.02
Score 0% 60%

Review

1

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

59% Answer Correctly

if the coefficient of friction is greater than one

at all times

when an attempt is made to move the box

only if normal force is present
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).

2

Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

increase, increase

increase, decrease

decrease, decrease

decrease, increase
Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

3 If the handles of a wheelbarrow are 1.0 ft. from the wheel axle and the load is concentrated at a point 1.5 ft. from the axle, how many pounds of load will a 180 lbs. force lift?
47% Answer Correctly
120
48
274.2
270
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 resistance force:
\( F_r = \frac{F_e d_e}{d_r} \)
\( F_r = \frac{180 \times 1.0}{1.5} \)
\( F_r = \frac{180.0}{1.5} \)
\( F_r = 120 \)
4

The standard unit of energy is the:

73% Answer Correctly

Horsepower

Watt

Joule

Volt
Solution

The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).

5

Power is the rate at which:

62% Answer Correctly

work is done

friction is overcome

input force is transferred to output force

potential energy is converted into kinetic energy
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.