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Sample Practice Test Questions
The radius of the axle is 3, the radius of the wheel is 4, and the blue box weighs 35 lbs. What is the effort force necessary to balance the load?
The mechanical advantage of a wheel and axle is the input radius divided by the output radius:
MA = \( \frac{r_i}{r_o} \)
In this case, the input radius (where the effort force is being applied) is 4 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{4}{3} \) = 1.33
MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{35 lbs.}{1.33} \) = 26.32 lbs.
Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?
do the work in 2 minutes
Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.
The formula for volume of a cube in terms of height (h), length (l), and width (w) is which of the following?
h x l x w
A cube is a rectangular solid box with a height (h), length (l), and width (w). The volume is h x l x w and the surface area is 2lw x 2wh + 2lh.
An inductor __________ changes in the electric current flowing through it.
resists
An inductor is coiled wire that stores electric energy in the form of magnetic energy and resists changes in the electric current flowing through it. If current is increasing, the inductor produces a voltage that slows the increase and, if current is decreasing, the magnetic energy in the coil opposes the decrease to keep the current flowing longer. In contrast to capacitors, inductors allow DC to pass easily but resist the flow of AC.
What is work?
The movement of an object by a force
Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.
A = 5 ft., the green box weighs 50 lbs., and the blue box weighs 80 lbs. What does distance B need to be for this lever to balance?
fAdA = fBdB
For this problem, the equation becomes:
50 lbs. x 5 ft. = 80 lbs. x dB
dB = \( \frac{50 \times 5 ft⋅lb}{80 lbs.} \) = \( \frac{250 ft⋅lb}{80 lbs.} \) = 3.13 ft.
Which of blood component fights infection?
white blood cells
Blood is created in bone marrow and is made up of cells suspended in liquid plasma. Red blood cells carry oxygen, white blood cells fight infection, and platelets are cell fragments that allow blood to clot.
Ignition timing is measured in number of degrees:
before top dead center
Ignition timing defines the point in time at the end of the compression stroke that the spark plug fires. Measured in number of degrees before top dead center (BTDC), the exact point that the spark plugs initiate combustion varies depending on the speed of the engine. The timing is advanced (the spark plugs fire a few more degrees BTDC) when the engine is running faster and retarded when it's running slower.
If angle a = 53° and angle b = 27° what is the length of angle d?
An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:
d° = b° + c°
To find angle c, remember that the sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 53° - 27° = 100°
So, d° = 27° + 100° = 127°
A shortcut to get this answer is to remember that angles around a line add up to 180°:
a° + d° = 180°
d° = 180° - a°
d° = 180° - 53° = 127°