Dynamics Flashcards
(25 cards)
Name Newton’s First Law with an example.
An object that is moving uniformly will continue moving uniformly, and an object that is at rest will stay at rest, unless acted on by an unbalanced external force.
If you are in a car that comes to a sudden stop, you will jerk forward as your body wishes to continue moving forward.
Name Newton’s Second Law.
The net force on a given object is equal to its mass multiplied by its acceleration. Hence, mass and acceleration are inversely proportional.
Name Newton’s Third Law with an example.
Every action force has an equal and opposite reaction force.
When you jump, you apply a force downwards on the ground, which applies a force upwards on you.
Define inertia.
Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes the velocity to change. Objects with a greater mass have greater inertia.
Inertia will resist sudden changes in motion, but is lenient if the change happens slowly.
What is static friction?
Static friction is the force of friction that opposes attempted motion. It increases up to a certain maximum threshold, after which point motion begins.
The maximum force of static friction is the coefficient multiplied by the normal force. Prior, it is equal to the opposite forces.
What is kinetic friction?
Kinetic friction is the force of friction that opposes actual motion. It is constant.
Describe the buoyancy force equation.
density of displaced fluid * volume of displaced fluid * gravitational constant
Default units for mass, volume, distance, and time:
kg, kg/m^3, m, s
Ways to state physics:
Fnet(y) = 0
Assume UCM
Planetary orbits are elliptical. When closer to the Sun, the orbit:
speeds up
Centripetal force is always the:
net force
The minimum speed for UCM is
the speed at which v = sqrt(gr)
Alternatively, when F(t) at the top is 0.
Mass and radius of Earth:
5.98 * 10^24 kg
6.38 * 10^6 m
Stoke’s Law says:
Viscous drag on a sphere with a uniform surface in a uniform liquid in a column only depends on speed of object, viscosity of the liquid, and radius of object
What is viscous drag?
A force opposing the motion of an object in a fluid. It is variable based on:
- speed of the object
- shape of the object
- cross sectional area of the object
- identity and features of the fluid
- surface material of the object
- surface of the object
Units of viscosity?
Poise, Pascal second (Pa s), kg/ms
Represented with the n looking symbol
Curved roads are banked towards the centre because:
the normal force should be centre seeking
If an object is only partially submerged in the liquid, find the %submerged of total volume through:
density(object) / density(fluid)
Buoyancy is caused by:
upwards pressure force always exceeds downwards pressure force
All objects with mass are:
Force is proportional to:
attracted to other obejcts with mass. Force is proportional to their respective masses; thus if either mass doubles then the force doubles
Universal gravitational force is inversely proportional to:
distances between centrepoints squared
Weightlessness refers to
the lack of a normal force
Pressure is:
- amount of force / unit area
- proportional to depth
Geosynchronous
same orbit time as the Earth
