Question

Suppose two cars depart from a four-way intersection at the same time, one heading north and the other heading west. The car heading north travels at the steady speed of 20 ft/sec and the car heading west travels at the steady speed of 36 ft/sec.
(a) Find an expression for the distance between the two cars after t seconds. (Round your coefficients to one decimal place as needed.) in ft
(b) Find the distance in miles between the two cars after 3 hours 15 minutes. (Round your answer to one decimal place.) in mi
(c) When are the two cars 1 mile apart? (Round your answer to one decimal place.)in sec

Answer 1

since distance = speed * time,
(a) d = √((20t)^2 + (36t)^2) = 4√106 t
(b) use t=3*3600+15*60 = 11,700 in (a) and divide by 5280
(c) solve for t when d = 5280