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Physics
Problem
Two identical cars travel along the same straight road. Car A covers
60
km
60\,\text{km}
60
km
at
30
km/h
30\,\text{km/h}
30
km/h
and then another
60
km
60\,\text{km}
60
km
at
60
km/h
60\,\text{km/h}
60
km/h
. A student claims that the average speed of Car A is
(
30
+
60
)
/
2
=
45
km/h
(30+60)/2 = 45\,\text{km/h}
(
30
+
60
)
/2
=
45
km/h
. Explain briefly why this claim is incorrect.
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