Question

The time is takes an object to move a certain distance is inversely propotional to the speed that it's travelling at.

it takes a car 12 minutes to travel the length of a road if it goes at an average speed of 60mph

a) How long would it take the car to travel down the same road if it travelled at an average speed of 30mph
B) if it takes the car 36 minutes to drive down the road, what will it's average speed

Answer 1

a) 24 minutes

b) 20 mph

Explanation:

Speed - distance -time:

time= 12 min

`\sf = (12)/(60) \ hour`

speed = 60 mph

`\sf \boxed{distance =speed * time}`

`\sf = 60 * (12)/(60)\\\\ = 12 \ m`

a) Speed = 30 mph

`\sf \boxed{time = (distance)/(speed)}`

`\sf = (12)/(30)\\\\ = (2)/(5) \ hour\\\\ = (2)/(5)*60\\\\= 2 * 12\\\\= 24 \ minutes`

It will take 24 minutes.

c) time = 36 minutes

`\sf = (36)/(60) \hour`

`\sf \boxed{speed= (distance)/(time)}`

`\sf = (12)/( (36)/(60))\\\\\\ = 12* (60)/(36)\\\\= 20 \ mph`

Average speed = 20 mph