A bird flies at 10ms(^{-1}) for 3s, 15ms(^{-1}) for 3s and 20 ms(^{-1}) for 4s. Calculate the bird’s average speed
-
A.
4.5 ms-1 -
B.
15.0 ms-1 -
C.
15.5 ms-1 -
D.
51.7 ms-1
Correct Answer: Option C
Explanation
Av. speed = (frac{3 times 15 + 3 times 10 + 4 times 20}{3 + 3 + 4})
= 15.5 ms(^{-1})