Dynamics Flashcards
What is dynamics?
Dynamics is the study of motion and the force causing the motion.
What is a force?
Force is a push or pull of one object on another.
What are the two categories of force?
Applied force and Net/Resultant force and resistive force.
What are the two types of applied forces?
Friction and Drag force.
What are the two types of drag forces?
Air resistance and Fluid Drag.
What are the types of resultant/net force?
Weight
Tension
Upthrust
Normal Reaction force
Centripetal force
What is an applied force?
a force exerted by an external source is called an applied force.
Give examples of applied force.
Force of a horse on a cart
Force of Friction between a road and tire on a car.
What is a resistive force?
Resistive forces are forces that always oppose motion.
Define Friction.
A stopping force between two sliding surfaces due to interlock between surfaces is called friction.
What are the factors which affect friction?
Nature of surfaces
Normal reaction/Contact Force
What are some benefits of friction?
Friction is beneficial when we need to stop a car or bike etc.
Friction is important when tying a knot.
Friction between the road and the tire and a shoe and the track to help you move.
What are some disadvantages of friction?
We need to spend fuel to overcome friction.
Friction generates unwanted heat.
Friction causes wear and tear in mechanical parts.
Define Tension.
tension is a pulling force exerted by a rod, chain or rope.
Tension acts along the rope away from both ends.
In one rope there can only be one tension.
Define Weight.
Weight is the gravitational force of nearby mass. (usually nearest celestial mass)
Weight=mass x gravitational field strength.
What can force do?
●Force can change motion, accelerate, decelerate or change direction of motion.
●Force can generate heat (Friction)
●Force can turn an object, produce moment or turning affect.
●Force can deform an object. (check notes)
●Force can cause pressure.
Define drag force.
When a solid moves in a fluid, it exerts force on molecules of fluid. The molecules of fluid exert an equal but opposite force on the solid object as a reaction. This reaction force is called drag force.
What is the name of drag force to due to air?
Drag force due to air is known as air resistance.
What does drag force depend upon?
Drag force depends upon:
Velocity/Speed of motion=D∝v^2
Area of front of the object=D∝A or D∝d^2 (where d is the diameter square)
The density of the medium D∝ρ