a car travells from stop A to stop B with a speed of 30 km h-1 and than returns back to A with the speed of 50 km h-1. find (1) displacement of the car. (2) distance travelled by the car. (3) average speed of the car
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Displacement of the car is zero as it is returned to its initial position.
1) Distance travelled by the car
We have to know how long it took for the round trip to find the distance:Lets assume it took 12 hrs for the round trip:let d = the one way distance
Write a time equation; time = dist/speed = d/30+d/50= 12
multiply by 150
150*d/30+ 150*d/50= 150(12)
Cancel the denominators and you have:5d + 3d = 18008d = 1800d = 1800/8d = 225 m one way or a total of 450 m round trip
Confirm this find the actual time each way225/30 = 7.5 hrs
225/50 = 4.5 hrs
total hr: 12
2) average speed
v = 30 km/h
t = s/v
t = x/30 h
v= 50km/h
s=x
t= x/50 h
total distance= x+x =2x
total time= x/30 +x/50 = 5x +3x/150 = 8x/150
average speed = 2x / (8x/150)
= 2x * 150/8x = 37.5 km/h
1) Distance travelled by the car
We have to know how long it took for the round trip to find the distance:Lets assume it took 12 hrs for the round trip:let d = the one way distance
Write a time equation; time = dist/speed = d/30+d/50= 12
multiply by 150
150*d/30+ 150*d/50= 150(12)
Cancel the denominators and you have:5d + 3d = 18008d = 1800d = 1800/8d = 225 m one way or a total of 450 m round trip
Confirm this find the actual time each way225/30 = 7.5 hrs
225/50 = 4.5 hrs
total hr: 12
2) average speed
v = 30 km/h
t = s/v
t = x/30 h
v= 50km/h
s=x
t= x/50 h
total distance= x+x =2x
total time= x/30 +x/50 = 5x +3x/150 = 8x/150
average speed = 2x / (8x/150)
= 2x * 150/8x = 37.5 km/h
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