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In kinematics, displacement refers to how far an object has traveled from its starting point, considering only its direction and magnitude. It is a vector quantity, meaning it has both magnitude and direction. For example, if a motorist travels north, stops, and then continues the journey north, the displacement will be measured solely in that direction.
In the example exercise, the displacement is calculated in two parts:

• The first segment involves traveling at a speed of 85.0 km/h for an adjusted time of 0.583 hours, resulting in a displacement of 49.6 km.
• The second segment of the journey consists of a direct travel of 130 km north.

By adding both segments together, we calculate the total displacement as 179.6 km, showing the overall distance north, from the starting point to the ending point.

Average velocity is a key concept in studying motion. It is the total displacement divided by the total time of travel. Unlike average speed, which ignores direction and only considers distance, average velocity is sensitive to the direction of travel.
To find average velocity, you'd use the formula: \[ \text{Average Velocity} = \frac{\text{Total Displacement}}{\text{Total Time}} \]In a scenario where a motorist starts, stops, and continues his journey, two displacements and several intervals of time are involved. In our case:

• The total displacement is 179.6 km.
• The total time spent is 2.83 hours (after conversions from minutes to hours).

Dividing these gives an average velocity of 63.5 km/h. This value simplifies the motion into a single speed, in the given direction, considering all fluctuations during the trip.

Time conversion is an essential step when calculating kinematics problems, especially when different units of time are involved, such as minutes and hours.
In our example, the motorist's travel times are given in minutes and hours, where conversions between these units are required to maintain consistency, since speeds are usually expressed in terms of hours. To convert minutes to hours, we divide by 60 because there are 60 minutes in an hour.
For the exercise:

• 35 minutes is converted to 0.583 hours (by calculation: 35/60).
• 15 minutes is converted to 0.250 hours (by calculation: 15/60).

Adding all these correctly converted time segments gives the total time for the journey, which is 2.83 hours. Correctly handling these conversions is crucial for accurately calculating other quantities, like average velocity.