The atomic number of Aluminum is 13. The atomic number represents the number of protons in an atom.
Answer:
Mary will have to wait for 63.2 seconds
Explanation:
Time required for the apple to drop from a height of 17.0 m above the ground to 1.65 m above the ground is given by the formula below:
t = √2h/g where h is height through which the object falls, g is acceleration due to gravity
h = 17.0 - 1.65 = 15.35 m
g = 9.8 m/s²
t = √(2 * 15.35/9.8)
t = 1.77 s or approximately 1.8 s
Time taken for bill to get to the point below Mary's window is given below;
time taken = distance/velocity
distance = 130 m; velocity = 2.0 m/s
time taken by Bill = 130/2.0 = 65 s
Therefore, Mary will have to wait for (65 - 1.8) s = 63.2 seconds
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