Physics Flashcards chapter 1-4

Flashcards based on lecture notes covering kinematics, vectors, and forces.

What is Position?

The location of an object as measured on a coordinate system.

What is Distance?

The total length of travel from beginning to end; always positive.

What is Displacement?

The change in position (Δx = x - x₀).

What does the sign of displacement indicate?

Indicates the direction of motion.

What is average speed?

Distance divided by elapsed time.

What is average velocity?

Displacement divided by elapsed time.

How is average velocity represented graphically?

The slope of a line connecting two points on an x-versus-t plot.

What is instantaneous velocity?

The average velocity over shorter and shorter time intervals (v = lim Δx/Δt as Δt approaches 0).

How is instantaneous velocity represented graphically?

The slope of a tangent line at a given instant of time on an x-versus-t plot.

What is average acceleration?

The change in velocity divided by the elapsed time.

What is instantaneous acceleration?

The limit of the average acceleration over shorter and shorter time intervals (a = lim Δv/Δt as Δt approaches 0).

How is instantaneous acceleration represented graphically?

The slope of a tangent line at a given instant of time on a v-versus-t plot.

What are freely falling objects?

Objects move under the influence of gravity alone once released.

What is one meter defined as?

Distance traveled by light in a vacuum in 1/299,792,458 second.

What is one kilogram defined as?

The mass of a metal cylinder kept at the International Bureau of Weights and Measures.

What is one second defined as?

The time required for a particular type of radiation from cesium-133 to undergo 9,192,631,770 oscillations.

What is the dimension of a quantity?

The type of quantity it is (e.g., length [L], mass [M], or time [T]).

When is an equation dimensionally consistent?

Each term in it has the same dimensions.

What are significant figures?

The number of digits reliably known, excluding digits that simply indicate the decimal place.

What is round-off error?

Discrepancies caused by rounding off numbers in intermediate results.

How do you convert units?

Multiply by the ratio of two units.

What is an order-of-magnitude calculation?

An estimate designed to be accurate to within the nearest power of ten.

What is a scalar?

A physical quantity that can be represented by a numerical value only.

What are vectors?

Quantities that require a direction in addition to the numerical value.

What is a good general approach to problem solving in physics?

Read, sketch, visualize, strategize, identify equations, solve, check, explore limits.

What is a scalar?

A number with appropriate units.

What is a vector?

A quantity with both a magnitude and a direction.

What is the x component of Vector A?

A cos θ, where θ is measured relative to the x axis.

What is the y component of Vector A?

A sin θ, where θ is measured relative to the x axis.

How is the magnitude of Vector A calculated?

√(Ax² + Ay²)

How is the direction angle of Vector A calculated?

tan⁻¹(Ay/Ax), where θ is measured relative to the x axis.

How to add vectors graphically?

Place them so that the tail of B is at the head of A; C = A + B is the arrow from the tail of A to the head of B.

How to add vectors using the component method?

If C = A + B, then Cx = Ax + Bx and Cy = Ay + By.

What is the x unit vector?

A dimensionless vector of unit length in the positive x direction.

What is the y unit vector?

A dimensionless vector of unit length in the positive y direction.

What does the position vector do?

Points from the origin to a particle's location.

What is the displacement vector?

The change in position (Δr = rf - ri).

What direction does the velocity vector point?

Points in the direction of motion and has a magnitude equal to the speed.

What does the acceleration vector indicate?

Indicates how quickly and in what direction the velocity is changing; it need not point in the direction of motion.

How do you calculate the velocity of object 1 relative to object 3?

v₁₃ = v₁₂ + v₂₃, where object 2 can be anything.

Describe frictional forces.

Frictional forces are due to the microscopic roughness of surfaces in contact. They are independent of area of contact and relative speed.

What is kinetic friction?

Experienced by surfaces that are in contact and moving relative to one another.

What is the force of kinetic friction?

fk = μkN, where μk is the coefficient of kinetic friction and N is the magnitude of the normal force.

What is static friction?

Experienced by surfaces that are in static contact.

What is the maximum force of static friction?

fs,max = μsN, where μs is the coefficient of static friction and N is the magnitude of the normal force; can have any magnitude between zero and its maximum value.

What function do strings and springs serve?

Strings and springs provide a common way of exerting forces on objects.

What is tension?

The force transmitted through a string; it is the same throughout the length of an ideal string.

What is Hooke's Law?

F = -kx.

When is an object in translational equilibrium?

The net force acting on it is zero.

Describe connected objects.

Objects connected by strings have the same magnitude of acceleration.

What is the centripetal acceleration of an object moving with speed v in a circle of radius r?

a = v²/r directed toward the center of the circle.

What is the force required for an object of mass m to undergo circular motion?

fcp = macp = mv²/r.