ASVAB Mechanical Comprehension Practice Test 328804 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.15
Score	0%	63%

Review

Drag is a type of:

82% Answer Correctly

	kinetic energy
	potential energy
	work
	friction

Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.

2 What is the power output of a 5 hp engine that's 80% efficient?

40% Answer Correctly

	733.3 \( \frac{ft⋅lb}{s} \)
	2200 \( \frac{ft⋅lb}{s} \)
	550 \( \frac{ft⋅lb}{s} \)
	16 \( \frac{ft⋅lb}{s} \)

Solution

\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), P_i becomes 5 hp x 550 \( \frac{ft⋅lb}{s} \) = 2750 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{80 \times 2750 \frac{ft⋅lb}{s}}{100} \) \( = \frac{220000 \frac{ft⋅lb}{s}}{100} \) = 2200 \( \frac{ft⋅lb}{s} \)

Which of the following is the formula for gravitational potential energy?

61% Answer Correctly

	\(PE = mgh\)
	\(PE = { 1 \over 2} mv^2\)
	\(PE = mg^2h\)
	\(PE = { 1 \over 2} mg^2\)

Solution

Gravitational potential energy is energy by virtue of gravity. The higher an object is raised above a surface the greater the distance it must fall to reach that surface and the more velocity it will build as it falls. For gravitational potential energy, PE = mgh where m is mass (kilograms), h is height (meters), and g is acceleration due to gravity which is a constant (9.8 m/s²).

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).

A watt is the unit for which of the following?

71% Answer Correctly

	energy
	mechanical advantage
	power
	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.