Chapter 2: Dynamics Flashcards
Forces, Normal reaction, Friction, Newton's laws of motion, Terminal Velocity, Center of Gravity, Stability, Moments
What is a force?
An action that will change the motion of an object when unopposed
What is the normal reaction, and in what direction does it act?
It is a reaction to an applied force, and is always perpendicular to the surface along the place the force is acted on
What is friction?
A force that opposes motion between surfaces in contact
What is the difference between sliding and rolling friction?
Sliding friction acts against the direction of motion while rolling friction acts with the direction of motion
Is friction dependent on surface area?
No
What is tension?
A pull force exerted by a string, spring or rope on an object attatched to it
What are some types of non-contact forces?
Gravity, Electromagnetic, Electrostatic, Strong and weak nuclear forces
What is Newton’s first law of motion?
Every body contrinues in its state of motion unless an external force acts on it
What is Newton’s second law of motion?
Force applied = mass of object x acceleration of object
What is Newton’s third law of motion?
Every action has an equal and opposite reaction
What is inertia?
The property of a body that resists a change in the state of rest or uniform motion
What is terminal velocity?
The maximum velocity of a falling object in fluid medium, or when air resistance is equal to the weight of an object
What is the acceleration at terminal velocity?
0
What is the effect of mass of an object on its terminal velocity?
The greater the mass of an object, the higher its terminal velocity
What is the effect of surface area of an object on its terminal velocity?
The smaller the surface area of an object, the higher its terminal velocity
What is the center of gravity
The point of an object where the whole weight of an object seems to act upon
Where is the center of gravity if the object is hanging freely at rest?
The center of gravity is in line with the pivot
What is stability?
The ability of an object to return to its original position
When will an object topple?
When the line of action of the force passing through the center of gravity exceeds the base of the object
How can stability be increased?
Loweing the center of gravity and increasing base area
What are the three types of equilibrium?
Stable, Unstable and Neutral
What is a moment?
The product of the force and the perpendicular distance from the line of action of the force to the pivot
What is the principal of moments?
When a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot
