Kinematics Notes and Flashcards

Kinematics Cram Sheet

Distance is the total length that an object in motion covers.

Displacement is a vector quantity that indicates the change in position that an object moves in a particular direction.

Average speed is the distance covered per unit time.

Average velocity is the displacement divided by the time interval.

The slope of a position (distance) time graph is velocity (speed).

The slope of a velocity time graph is acceleration.

Acceleration occurs whenever there is a change of speed or direction of motion.

The direction an object accelerates is not necessarily the same direction it moves.

If acceleration and velocity are parallel (same signs), the object speeds up; antiparallel (opposite signs),

slow down; right angles, circular constant speed. Anything else is some kind of curved path.

Parabolas on position-time graphs mean non-zero-slope straight lines on velocity-time graphs which mean

zero slope (horizontal) lines on acceleration-time graphs.

Area under a velocity time graph is displacement (change in position).

Area under acceleration time graph is velocity change in velocity). Areas below the time axis represent negative displacements.

Free fall problems can be solved like other acceleration problems by substituting 'a' for 'g' = 9.8 m/s2. The sign of 'g' is (-) if up is chosen as the positive direction. It is OK to use 'g' = 10 m/s2 in the multiple-choice section of the exam.

Projectile motion:

- horizontal and vertical components are independent,

- the horizontal component of the velocity remains constant,

- the vertical component has constant acceleration 'g',

- only the vertical component of the velocity at the maximum height is zero,

- for projectiles fired at an angle you may assign negative signs to all vectors going down.

A ball rolled off a horizontal table will take the same amount of time to hit the ground as another dropped from the same height.

As a falling object approaches terminal velocity, speed increases and acceleration decreases.

Uniform Circular Motion:

- speed is constant, velocity is changing v = 2πr/T = 2πrf, direction is tangent to the path

- acceleration ac = vt

2/r is centripetal or toward center.

Acceleration down a ramp:

object slides down a ramp due to the action of gravity, accelerates parallel to the ramp a// = g sin 