Using the equation of motion, it can be determined that Alexander travels at an average speed of 25.57 m/s while operating a bike.
What are motion equations?Equations of motion are equations that explain how a physical system behaves in terms of how its motion changes over time.
The three equations are,
v = u + at
v² = u² + 2as
s = ut + 1/2at²
Now for the given question,
For the initial 4.05 seconds, initial velocity = 0, acceleration = 12.9 m/s and time taken = 4.05 s
Using first equation of motion,
v = u + at
v = 0 + 12.9(4.05) = 52.245 m/s
He then kept this speed up for 8.48 seconds.
For the last 5.60 seconds, final velocity = 0, initial velocity = 52.245 m/s
Acceleration = (0-52.245)/5.60 = -9.329 m/s
Distance travelled in 4.05 seconds is given as follows:
s = u t + 1/2(at²)
= 0 + 1/2(12.9)(4.05)²
= 105.79 m
Distance travelled in 8.48 seconds = 52.245 × 4.05 = 211.592 m
Distance travelled in 5.60 seconds is given as follows:
s = u t + 1/2(at²)
s = 52.245(5.60) + 1/2(-9.329)(5.60)²
= 146.294 m
Total distance travelled =105.79 + 211.592 + 146.294 = 463.676 m
Average speed = Total distance/Total time = 463.676/(4.05+8.48+5.60)
= 25.57 m/s
Therefore, average motion speed for Alexander while riding a bike is 25.57 m/s which is calculated by using the equation of motion.
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