richiesmasher
Junior Member
 Joined
 Dec 15, 2017
 Messages
 111
A driver starting a car from rest accelerates uniformly to a speed of 30km/h in 2 minutes.
She maintains this speed for another 5 minutes then applies the brakes and decelerates uniformly to rest in 1 minute.
Now they ask to draw a velocity time graph, no axes given, just a sketch, which I did.
Then they ask calculate the acceleration in km/h[SUP]2[/SUP] for the first two minutes which I did and it is 900km/h[SUP]2[/SUP]
Then calculate the decelration in the last 2 minutes so it would be 0 1800km/h[SUP]2[/SUP] = 1800km/h[SUP]2
[/SUP]
Now the part which is troubling me, they say calculate the total distance traveled in km. I know the area under the graph which is usually a trapezium is the total distance, however they just asked for a sketch, I don't really have any specific scales.
Their answer is 3(1/3)km but I'm not getting that.
I'm using this logic, for a period she traveled 5 minutes at 30km/h, so in 5 minutes the distance traveled would be 30km/h * 5/60 hours = 2.5 km.
Now I have to figure out the distance she traveled for the part where she accelerated and decelerated.. and yea I'm stuck.
She maintains this speed for another 5 minutes then applies the brakes and decelerates uniformly to rest in 1 minute.
Now they ask to draw a velocity time graph, no axes given, just a sketch, which I did.
Then they ask calculate the acceleration in km/h[SUP]2[/SUP] for the first two minutes which I did and it is 900km/h[SUP]2[/SUP]
Then calculate the decelration in the last 2 minutes so it would be 0 1800km/h[SUP]2[/SUP] = 1800km/h[SUP]2
[/SUP]
Now the part which is troubling me, they say calculate the total distance traveled in km. I know the area under the graph which is usually a trapezium is the total distance, however they just asked for a sketch, I don't really have any specific scales.
Their answer is 3(1/3)km but I'm not getting that.
I'm using this logic, for a period she traveled 5 minutes at 30km/h, so in 5 minutes the distance traveled would be 30km/h * 5/60 hours = 2.5 km.
Now I have to figure out the distance she traveled for the part where she accelerated and decelerated.. and yea I'm stuck.
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