Unit 1 Test Extra Practice - Kinematics and Free-Body Diagrams

Vocabulary flashcards covering key concepts from the lecture notes on average speed, free-body diagrams, net force, acceleration, friction, and related ideas.

Average speed

Total distance traveled divided by the total time taken; does not include direction. Example: 16,000 m in 2,580 s gives about 6.20 m/s.

Free-body diagram

A diagram that shows all external forces acting on an object (e.g., gravity, normal force, friction, applied forces, tension).

Net force

The vector sum of all forces acting on an object; determines acceleration via F_net = m a.

Acceleration

The rate of change of velocity; a = Δv/Δt; units m/s^2; direction follows the net force.

Friction

A force that opposes motion between two contacting surfaces; can be static or kinetic.

Normal force

The perpendicular contact force exerted by a surface on an object.

Gravity (weight)

The force pulling objects toward Earth; F_g = m g; g ≈ 9.8 m/s^2 (often approximated as 10 m/s^2 in problems).

Mass

A measure of the amount of matter in an object; relates to inertia; measured in kilograms; weight depends on gravity via F_g = m g.

Newton's Second Law

The net force on an object equals its mass times acceleration: F_net = m a.

Velocity vs. Speed

Speed is how fast an object is moving (magnitude of velocity); velocity includes both speed and direction.

Equilibrium

A state in which the net force on an object is zero, resulting in no acceleration.

Free fall velocity under gravity

If starting from rest, velocity after time t is v = g t (g ≈ 9.8 m/s^2). For example, after 8 s, v ≈ 78.4 m/s downward.

Applied force

A force exerted on an object by an agent (e.g., a push or pull).

Kinematic relation (s = u t + 0.5 a t^2)

Displacement under constant acceleration from initial velocity u over time t: s = u t + 0.5 a t^2. Also, final velocity v = u + a t.