Physics

# Section Summary

PhysicsSection Summary

## 2.1Relative Motion, Distance, and Displacement

• A description of motion depends on the reference frame from which it is described.
• The distance an object moves is the length of the path along which it moves.
• Displacement is the difference in the initial and final positions of an object.

## 2.2Speed and Velocity

• Average speed is a scalar quantity that describes distance traveled divided by the time during which the motion occurs.
• Velocity is a vector quantity that describes the speed and direction of an object.
• Average velocity is displacement over the time period during which the displacement occurs. If the velocity is constant, then average velocity and instantaneous velocity are the same.

## 2.3Position vs. Time Graphs

• Graphs can be used to analyze motion.
• The slope of a position vs. time graph is the velocity.
• For a straight line graph of position, the slope is the average velocity.
• To obtain the instantaneous velocity at a given moment for a curved graph, find the tangent line at that point and take its slope.

## 2.4Velocity vs. Time Graphs

• The slope of a velocity vs. time graph is the acceleration.
• The area under a velocity vs. time curve is the displacement.
• Average velocity can be found in a velocity vs. time graph by taking the weighted average of all the velocities.