First we write the kinematics equations:
a
v = a * t + vo
r = a * (t ^ 2/2) + vo * t + ro
For Wanda we have:
a = 0
v = 5
r = 5 * t
For Dave we have:
v = 10
r = 10 * (t-120)
To solve the system of equations, we graph both functions and see where
they intersect.
We have to intersect in the ordered pair:
(t, r) = (240, 1200)
answer
If they continue walking at these rates, Dave catch up to Wanda in 240s (1200 ft)
a
v = a * t + vo
r = a * (t ^ 2/2) + vo * t + ro
For Wanda we have:
a = 0
v = 5
r = 5 * t
For Dave we have:
v = 10
r = 10 * (t-120)
To solve the system of equations, we graph both functions and see where
they intersect.
We have to intersect in the ordered pair:
(t, r) = (240, 1200)
answer
If they continue walking at these rates, Dave catch up to Wanda in 240s (1200 ft)