Answer:
Average speed = 3.9 m /s
Step-by-step explanation:
Total distance = 400m
First 150m = 5.4m/s
[tex]speed = \frac{distance}{time} \\\\time = \frac{distance}{speed} = \frac{150}{5.4} = 27.78 \ s[/tex]
Second part :
S = 4.5m/s for 40s
[tex]Distance = speed \times time = 4.5 \times 40 = 180 \ m[/tex]
Third part :
Remaining distance = 400 - 150 -180 = 70m
Time taken to cover it = 34s
[tex]speed = \frac{distance}{time} = \frac{70}{34} = 2.05 \[/tex]
Speed = 2.05m/s
Find average speed
[tex]Average\ speed = \frac{total \ distance }{total \ time \ taken } \\\\Average \ speed = \frac{400}{101.78} = 3.93 \ mps[/tex]
Round to 1 dp => average speed = 3.9m /s
