To determine the velocity after 7 seconds from the start, we need to calculate the object's acceleration first. We can do this by using the average velocity formula:
Average velocity = (final velocity - initial velocity) / time
For the first 2 seconds, the object travels 20 meters, starting from rest. Therefore, the average velocity during this time is:
20 meters / 2 seconds = 10 meters per second
For the next 4 seconds, the object travels 160 meters. We can calculate the average velocity during this time as well:
160 meters / 4 seconds = 40 meters per second
To calculate the acceleration, we can use the formula:
Acceleration = (final velocity - initial velocity) / time
For the first 6 seconds, the object's initial velocity is 0 meters per second, and the final velocity is 40 meters per second. Therefore, the acceleration during this time is:
Acceleration = (40 meters per second - 0 meters per second) / 6 seconds Acceleration = 40 meters per second / 6 seconds Acceleration = 6.67 meters per second squared (rounded to two decimal places)
Now that we have the acceleration, we can determine the velocity after 7 seconds from the start using the equation of motion:
Velocity = initial velocity + acceleration * time
Since the object starts from rest, the initial velocity is 0 meters per second. Plugging in the values:
Velocity = 0 meters per second + 6.67 meters per second squared * 7 seconds Velocity = 0 meters per second + 46.69 meters per second Velocity = 46.69 meters per second
Therefore, the velocity of the object after 7 seconds from the start will be 46.69 meters per second.