Question

Two planes, which are 3480 miles apart, fly toward each other. Their speeds differ by 70mph. If they pass each other in 4 hours, what is the speed of each?

Answer 1

Step-by-step explanation:

Given:

S = 3 480 miles

ΔV = 70 mph

t = 4 h

_____________

V₁ - ?

V₂ - ?

Motion equations:

x₁ = V₁·t

x₂ = S - V₂·t

Equate:

x₁ = x₂

V₁·t = S - V₂·t

(V₁ + V₂)·t = S

We take into account that:

V₂ = V₁ +ΔV

(V₁ + V₁ + ΔV)·t = S

(2·V₁ + ΔV)·t = S

2·V₁ + ΔV = S / t

2·V₁ = S / t - ΔV

V₁ = (S / t - ΔV) /2 =(3 480 / 4 - 70) / 2 = 400 mph

V₂ = V₁ + ΔV = 400 + 70 =470 mph

Answer 2

Therefore, the speeds of the planes are 400,470 mph.

Step-by-step explanation:

Speed= Distance/time