CE 10224A - Science for CE (Physics) Flashcards Preview

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What are the 2 branches of dynamics?

- Kinematics (the study of the motion of point masses or rigid bodies. Focuses on calculating position, displacement, velocity and acceleration (not the forces causing them)

- Kinetics (the study of the forces that produce or change motion)


What are the types of friction?

Static frictional force, Fs - the force, opposing direction of motion and resulting in a static condition.

Kinetic friction, Fk - frictional force opposing motion as the object is moving.


How is static friction calculated?

𝐹𝑠 = πœ‡s𝐹Ν


Fs is static friction
πœ‡s is coefficient of static friction
FN is the normal force


How is kinetic friction calculated?

πΉπ‘˜ = πœ‡k𝐹N


Fk is kinetic friction
πœ‡k is coefficient of kinetic friction
FN is the normal force


In terms of friction coefficient, what causes an object to remain stationary?

When kinetic frictional force is less than force of static friction.


How is drag force calculated?

𝐷 = 1/2πΆπœŒπ΄π‘£^2

D is drag force
C is the drag coefficient
𝜌 is fluid density
A is cross-sectional surface area perpendicular to v
v is fluid velocity


How is centripetal force calculated?

𝑭𝒄 = π’Žπ’—πŸ / 𝒓


How is velocity and angular velocity calculated?

𝑣 = 2πœ‹π‘Ÿ / 𝑇

𝑣 = 2πœ‹π‘Ÿπ‘“

𝑣 = πœ”π‘Ÿ

πœ” = 2πœ‹ / 𝑇


How is centripetal acceleration calculated?

𝒂𝒄 = 𝝎^πŸπ‘Ÿ

𝒂𝒄 =𝒗^𝟐 / 𝒓


How are forces analysed in non-uniform circular motion?

If πΉπ‘‘π‘œπ‘‘ is acting at an angle, then this force causes a non-uniform circular motion

Analysis into x, y-axis components:

- There's a force directed towards the centre of the circle causing the centripetal acceleration, 𝒂𝒄

- A tangential force causes a tangential acceleration called 𝒂𝒕𝒂𝒏.

These accelerations are perpendicular to one another.


For non - uniform circular motion, how is total acceleration and angular acceleration calculated?

𝒂𝒄 = 𝝎^πŸπ‘Ÿ

𝒂𝒕𝒂𝒏 = 𝒅𝒗/𝒅𝒕 = π‘Ÿ π’…πŽ/𝒅𝒕

𝒂𝒕𝒐𝒕 = (𝒂𝒄^2 𝟐+𝒂𝒕𝒂𝒏^2)^1/2

π’‚π’‚π’π’ˆ= π’…πŽ/𝒅𝒕
= (πŽπŸβˆ’πŽπŸ) / (π’•πŸβˆ’π’•πŸ)


How are angular and tangential accelerations related?

𝒂𝒕𝒂𝒏 = π‘Ÿ*𝒂 π’‚π’π’ˆ


What's centrifugal force?

Ff, a β€˜β€™ reactive’’ force acting upon a body due to rotation, and on the opposite direction of the centripetal force, at an equal magnitude, away from the centre of rotation.


What's β€˜β€™apparent’’ centrifugal force?

Fapp, a force which pushes the object away from the centre of rotation.
This is not part of any interaction, but it is the objects inertia.


How is work done calculated?

π‘Š = πΉπ‘π‘œπ‘ πœƒ(π‘₯𝐡 βˆ’ π‘₯𝐴)

π‘Š = 𝑃(𝑉2 βˆ’ 𝑉1)


How is gravitational potential energy calculated?

[E = mgh]

U = mg(h2-h1)


How is kinetic energy calculated?

E = mv^2/2