A bus travels 30 km in 28 minutes at a constant speed - Leaving Cert Physics - Question a - 2020

To convert minutes into seconds, use the conversion factor where 1 minute = 60 seconds. Thus:

$28 ext{ minutes} = 28 imes 60 ext{ seconds} = 1680 ext{ seconds}$

Speed is calculated using the formula:

ext{Speed} = rac{ ext{Distance}}{ ext{Time}}

Using the converted values:

$ext{Distance} = 30000 ext{ m}$ $ext{Time} = 1680 ext{ s}$

Thus:

ext{Speed} \, \approx \, 17.86 ext{ m/s}$$

The velocity-time graph of the bus's journey would typically show a horizontal line at a constant speed for the duration of the journey, reflecting no change in velocity:

• The initial segment shows a constant speed (horizontal line).
• When the driver applies the brakes, there will be a sharp deceleration represented by a downward slope until the bus comes to a stop.
• The axes should be labeled with time on the x-axis and velocity on the y-axis.

Speed is defined as the rate at which an object covers distance and is a scalar quantity, meaning it only has magnitude (e.g., 30 m/s).

Velocity, on the other hand, is a vector quantity that involves both the speed of the object and its direction (e.g., 30 m/s to the north). Thus, while speed tells us how fast something is moving, velocity tells us how fast and in what direction it is moving.