Physics & math

Question 1

Distance

Answer 1

Scalar quantity that reflects the path traveled.

Question 2

Displacement

Answer 2

Vector representation of a change in position. It is path independent and is equivalent to the straight line distance between the start and end locations.

Question 3

Velocity

Answer 3

Vector representation of the change in displacement with respect to time.

Question 4

Dot Product

Answer 4

[a][b]cos(theta)

Multiplying two vectors using the dot product results in a scalar quantity.

Question 5

Cross Product

Answer 5

[a][b]sin(theta)
Multiplying two vectors using the cross product results in a vector quantity. The RHR is used to determine the resultant vector’s direction.

Question 6

Vector

Answer 6

Physical quantity with both magnitude and direction. (e.g. displacement, velocity, acceleration, and force)

Question 7

Scalar

Answer 7

Quantity without direction. (e.g. speed, coefficient of friction)

Question 8

SI units

Answer 8

meter, kilogram, second, ampere, mole, kelvin, candela

Question 9

Force

Answer 9

Push or pull that has the potential to result in an acceleration.

Question 10

Gravity

Answer 10

Attractive force between two objects as a result of their masses.

Question 11

Friction

Answer 11

Force that opposes motion as a function of electrostatic interactions at the surfaces of two objects.

Question 12

Static friction

Answer 12

Exists between two objects that are not in motion relative to each other.

0 <= fs =< mu(s)N

mu(s) = coefficient of static friction
mu(s) > mu(k) always b/c harder to get an object to start moving vs. keeping it moving.

Question 13

Kinetic friction

Answer 13

Exists between two objects that are in motion relative to each other.

fk = mu(k)N

Whereas static friction can take on many values,
kinetic friction is constant given a constant normal force and coefficient of kinetic friction.

Question 14

Mass

Answer 14

Measure of the inertia of an object - its amount of material.

Constant regardless of location (e.g. mass on Earth = mass on moon)

Question 15

Weight

Answer 15

Force experienced by a given mass due to its gravitational attraction to Earth.

Weight = mg

Question 16

Acceleration

Answer 16

Vector representation of the change in velocity over time.

Question 17

Newton’s first law / Law of inertia

Answer 17

An object will remain at rest or move with a constant velocity if there is no net force on the object.

F = ma = 0

Question 18

Newton’s second law

Answer 18

Any acceleration is the result of the sum of the forces acting on the object and its mass.

F = ma

Question 19

Newton’s third law

Answer 19

Any two objects interacting with one another experience equal and opposite forces a result of their interaction.

“Every reaction has an opposite and equal reaction.”

Fab = -Fba

Question 20

Linear Motion

Answer 20

Motion with constant acceleration. Includes free fall and motion in which the velocity and acceleration vectors are parallel or antiparallel.

Question 21

Projectile Motion

Answer 21

Contains both an x- and y- component. Assuming negligible air resistance, the only force acting on the object is gravity.

Separate into x and y components.

Parallel gravity = mgcos(theta)
Perpendicular gravity / Normal force = mgsin(theta)

Question 22

Inclined planes

Answer 22

2D movement; easiest to consider the dimensions as being parallel and perpendicular to the surface of the plane.

Normal force is perpendicular to the object.
Weight faces straight down the plane.

Question 23

Circular motion

Answer 23

Has radial and tangential dimensions. In uniform circular motion, the only force is the centripetal force, pointing radially inward. The instantaneous velocity vector always points tangentially.

The centripetal force exerts centripetal acceleration on the object, keeping it from going tangential to the circle (where its velocity vector points.)

Centripetal force = mv^2/r

Question 24

Free body diagrams

Answer 24

Representations of the forces acting on an object. Useful for equilibrium and dynamics problems.

Question 25

Translational equilibrium

Answer 25

Occurs in the absence of any net forces acting on an object. An object in translational equilibrium has a constant velocity and may or may not also be in rotational equilibrium.

Question 26

Rotational equilibrium

Answer 26

Occurs in the absence of any net torques acting on an object. Rotational motion may consider any pivot point, but the center of mass is most common. An object in rotational equilibrium has contstant angular velocity; on the MCAt, the angular velocity is usually 0.