Unit 1: Kinematics

Definitions

1

The total length of the path traveled by an object.

Distance

2

The rate at which an object changes its velocity.

Acceleration

3

The speed and direction of an object's motion.

Velocity

4

The location of an object relative to a reference point.

Position

5

The quantity defined as the change in position; has both magnitude and direction.

Displacement

Units and Symbols

1

The standard unit for time.

Second

2

The symbol commonly used for initial velocity.

v_i or v₀

3

The standard unit for acceleration

m/s²

4

The Greek letter that represents change in some quantity.

Delta

5

The quantity represented by the letter 'g' near the Earth's surface.

Acceleration due to gravity (9.8m/s² downward)

Graphical Analysis

1

On a position-time graph, the slope of the line represents this quantity.

Velocity

2

The slope of a velocity-time graph gives you this quantity.

Acceleration

3

On a velocity-time graph, the area under the curve represents this quantity.

Displacement

4

A horizontal line on a velocity-time graph indicates this type of motion.

Constant-Velocity Motion

5

A curved line on a position-time graph indicates this.

Acceleration is not zero

Equations

1

This equation is used to find final velocity without knowing displacement

v_f = v_i + at

2

This equation is used to find displacement without knowing final velocity

Delta r = v_it + 1/2 at²

3

This equation is used to find displacement without knowing time

v_f² - v_i² = 2a · Delta r

4

This equation is used to find average velocity when you know initial and final velocity

v_avg = ( v_i + v_f ) / 2

5

To solve a problem using the equations we learned, there's a special condition.

Acceleration is constant.

Problem Solving

1

A car goes from 0 to 60 mph in 6 seconds. Find its average acceleration's magnitude.

10 mph/s

2

A ball is dropped from rest. Its velocity after 2 seconds (use g ≈ 10 m/s² for simplicity).

20 m/s downward

3

A bike accelerates at 2 m/s² from rest for 5 seconds. This is the total distance traveled.

25 m

4

An object is thrown straight up. At the very top of its path, its velocity is?

0 m/s

5

A car moving at 20 m/s slams on the brakes and decelerates at 5 m/s². This is the distance it takes to stop.

40 m