Answer:
a) v'=0 , B) v'= 125 miles/h
Explanation:
This is a relative speed exercise, the speed of a body is
v ’= v - u
where v is the speed with respect to the Earth and u the speed of the reference frame with respect to which we want to calculate
a) with respect to a car traveling east at u = 60 miles / h
v ’= 60 -60
v ’= 0
with respect to this vehicle the speed of the car is zero
b) with respect to a truck traveling west at u = -65 miles / h
v = 60 - (-65)
v = 125 miles / h
