66 mph
Explanation:
Average speed is the rate of change of distance with time:
Average speed = 
Given parameters:
Starting point = 88mile marker
End of journey = 121mile marker
time = 30minutes = 0.5hr(60min = 1hr)
Solution:
The distance covered in this journey:
Distance = End of journey - starting point = 121 mile - 88 mile = 33mile
Average speed = 
= 66mph
The average speed of Sara's mum is 66mph
Learn more:
Average speed brainly.com/question/8893949
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Answer:
One mole of copper atoms has Avogadro number of copper atoms i.e. 6.022×10
23
atoms.
Given the mass of Copper is 6.4g
Number of Copper atoms in 6.4g =
molar mass
given mass
×Avogadro number
=
63.55
6.4
×6.022×10
23
copper atoms
=6.064×10
22
copper atoms
Explanation:
Answer: Objects with like charge repel each other.