| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.30 |
| Score | 0% | 66% |
Which of these is the formula for kinetic energy?
\(KE = {1 \over 2}mh^2\) |
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\(KE = {1 \over 2}mv^2\) |
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\(KE = {m \over v^2 }\) |
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\(KE = mgh\) |
Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.
The work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. This defines which of the following?
mechanical advantage |
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work-energy theorem |
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Pascal's law |
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conservation of mechanical energy |
The work-energy theorem states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. Simply put, work imparts kinetic energy to the matter upon which the work is being done.
An object's resistance to changes in direction is known as:
mass |
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inertia |
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kinetic energy |
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weight |
The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.
| 980 lbs. | |
| 482 lbs. | |
| 163.3 lbs. | |
| 490 lbs. |
This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:
Fede = Frdr
Plugging in the variables from this problem yields:
Fe x 5 ft. = 490 lbs. x 5 ft.
Fe = \( \frac{2450 ft⋅lb}{5 ft.} \) = 490 lbs.
Which of the following is the formula for torque?
τ = rF |
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τ = r/F |
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τ = F/r2 |
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τ = F/r |
Torque measures force applied during rotation: τ = rF. Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).