AP Physics Classical Mechanics & Kinematics

Question 1

What is the definition of velocity?

Accepted Answer

Speed in a specified direction

Answer

Velocity is a vector quantity that describes both the speed of an object and its direction of motion. Unlike speed, which only indicates how fast an object is moving, velocity provides a complete description of its motion. For example, '60 mph' is a speed, but '60 mph north' is a velocity, specifying both magnitude and direction.

Question 2

What is the acceleration of an object in free fall near the Earth’s surface?

Accepted Answer

9.8 m/s²

Answer

Near the Earth's surface, the acceleration of an object in free fall, neglecting air resistance, is approximately 9.8 m/s². This constant value, denoted as 'g', represents the rate at which gravity increases an object's downward velocity every second it falls. It's a fundamental constant used in many physics calculations involving gravity.

Question 3

What is the formula for calculating velocity in uniform motion?

Accepted Answer

v = Δx / Δt

Answer

In uniform motion, velocity (v) is defined as the rate of change of displacement over time. The formula v = Δx / Δt precisely represents this relationship, where Δx is the change in position (displacement) and Δt is the change in time. This equation allows for the calculation of average velocity over an interval or instantaneous velocity if the interval is infinitesimally small.

Question 4

How does friction affect the motion of an object?

Accepted Answer

Decreases speed

Answer

Friction is a force that opposes the relative motion between two surfaces in contact. When an object moves, friction acts in the opposite direction of its motion, converting kinetic energy into other forms like heat. This energy conversion results in a reduction of the object's speed or requires a continuous external force to maintain its motion.

Question 5

What is the difference between scalar and vector quantities?

Accepted Answer

Scalars have magnitude, vectors have magnitude and direction

Answer

The fundamental difference between scalar and vector quantities lies in their description. Scalar quantities are fully defined by their magnitude (size) alone, such as mass, temperature, or speed. In contrast, vector quantities require both magnitude and a specific direction for their complete description, examples include velocity, force, and displacement.

AP Practice Test

AP Practice Test

AP Physics Classical Mechanics & Kinematics