## Mechanical Comprehension Flash Card Set 439549

 Cards 10 Topics Boyle's Law, First-Class Lever, Inclined Plane, Kinetic vs. Static Friction, Mechanics, Normal Force, Power, Structural Loads, Torque, Universal Gravitation

#### Study Guide

###### Boyle's Law

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional". Expressed as a formula, that's $$\frac{P_1}{P_2} = \frac{V_2}{V_1}$$

###### First-Class Lever

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

###### Inclined Plane

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.

###### Kinetic vs. Static Friction

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).

###### Mechanics

Mechanics deals with motion and the forces that produce motion.

###### Normal Force

Normal force (FN) represents the force a surface exerts when an object presses against it.

###### Power

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. A 1 hp machine does 550 ft⋅lb of work in 1 second and 1 hp equals 746 watts.

Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects: $$\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}$$ . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s2.