A car traveled five miles in six minutes.What was its speed in miles per hour?
2 answers:
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Answer:
(a) ðz/ðt = 1500miles/hr
(b) 10minutes
Step-by-step explanation:
Let x rep plane one
Let y rep plane two
ðx/ðt = 1440miles/hr = speed of plane one
ðy/ðt = 420miles/hr = speed of plane 2
ðz/ðt = ? = rate of change of distance btw two plane moving at right angle to meet at point o...
See attachment
Since x² + y² = z²... equation 1
So therefore (240² + 70²) ^½= z = 250 miles = distance between two planes
Differential rate of equation 1 gives
(2x* ðx/ðt ) + (2y* ðy/ðt) = 2z* ðz/ðt
Substituting to get ðz/ðt
(2*240*1440) + (2*70*420) = 2*250*ðz/ðt
750000 = 500 ðz/ðt
ðz/ðt = 1500miles/hr
B.
Since v = d/t where d = distance = 250miles
t = time = ? = time needed for controller to divert one of e planes , v = 1500miles/hr
t = d/v = 250/1500 = 10minutes
