ASVAB Mechanical Comprehension Practice Test 469858 Results

Your Results Global Average
Questions 5 5
Correct 0 2.64
Score 0% 53%

Review

1

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

lower than

higher than

opposite

the same as


Solution

The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.


2

Which of the following statements about drag is false?

58% Answer Correctly

the amount of drag depends on the speed of an object

the amount of drag depends on the shape of an object

drag occurs during movement through a fluid

slower objects experience more drag than faster objects


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.


3

Which of the following statements about this pulley configuration is false?

48% Answer Correctly

Changes the direction of and multiplies the effort force

Mechanical advantage is the number of ropes that support the resistance

This is a block and tackle pulley configuration

Only multiplies the effort force


Solution

A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.


4

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

66% Answer Correctly

concentrated load

static load

impact load

dynamic 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.


5 If the handles of a wheelbarrow are 0.5 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
0
343.1
300
150

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:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{150 \times 1.0}{0.5} \)
\( F_e = \frac{150.0}{0.5} \)
\( F_e = 300 \)