SOLUTION: A car’s speed is 30 miles per hour, and it begins to slow down at a constant rate of 6 miles per hour every 4 seconds. a) Write a linear function that relates the speed of the car

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A car’s speed is 30 miles per hour, and it begins to slow down at a constant rate of 6 miles per hour every 4 seconds. a) Write a linear function that relates the speed of the car      Log On


   

Question 597401: A car’s speed is 30 miles per hour, and it begins to slow down at a constant rate of 6 miles per hour every 4 seconds.
a) Write a linear function that relates the speed of the car S with the time since it began slowing down t.
b) How fast will the car be going after 10 seconds?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(a)
+30+ mi/hr = +30%2F3600+ mi/sec
+30%2F3600+=+.008333+ mi/sec
+S+=+.008333+-+%28+6+%2F+%28+4%2A3600+%29%29+%2At+
+S+=+.008333+-+%28+3+%2F+%28+2%2A3600+%29%29+%2At+
+S+=+.008333+-+.0004166t+ mi/sec
--------------------------
(b)
After 10 sec:
+S+=+.008333+-+.0004166%2A10+ mi/sec
+S+=+.008333+-+.004166+ mi/sec
+S+=+.004167+ mi/sec
+S+=+.004167%2A3600+ ( mi/sec )x( sec/hr )
+S+=+15.001+ mi/hr
The car will be going about 15 mi/hr