| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.25 |
| Score | 0% | 65% |
Which of these is the formula for kinetic energy?
\(KE = {m \over v^2 }\) |
|
\(KE = {1 \over 2}mh^2\) |
|
\(KE = {1 \over 2}mv^2\) |
|
\(KE = mgh\) |
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.
Which of these is the formula for force?
F = am2 |
|
F = m/a |
|
F = ma |
|
F = a/m |
Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.
Concurrent forces:
pass through a common point |
|
act in a common plane |
|
act along the same line of action |
|
act in a common dimension |
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
The mechanical advantage of a wheel and axle is equal to the:
difference in the lengths of the axles |
|
length of the axle |
|
difference in the diameters of the wheels |
|
ratio of the diameters of the wheels |
A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.
Power is the rate at which:
potential energy is converted into kinetic energy |
|
work is done |
|
friction is overcome |
|
input force is transferred to output force |
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.