Hello on speed time graphs, I am always having problems with the times that they give. For example, lets look at this problem:
A car moves along a horizontal straight road, passing two points A and B. At A the speed
of the car is 15 m s–1. When the driver passes A, he sees a warning sign W ahead of him,
120 m away. He immediately applies the brakes and the car decelerates with uniform
deceleration, reaching W with speed 5 m s–1. At W, the driver sees that the road is clear. He
then immediately accelerates the car with uniform acceleration for 16 s to reach a speed
of V m s–1 (V > 15). He then maintains the car at a constant speed of V m s–1. Moving at
this constant speed, the car passes B after a further 22 s.
(a) Sketch, in the space below, a speed-time graph to illustrate the motion of the car as it
moves from A to B.
When sketching these graphs, I am always having troubles distinguishing between the meaning of "for 16 seconds " and "further 22 seconds". If it says "for" does that mean that the time is for that particular block and if they say "further " does that mean that you add on the time from the end of the previous block.
I got the right answers but it was simply I guess due to chance. I feel i dont have the real understanding. "for " and further' is always getting me confused. HELPPPPPP>?
A car moves along a horizontal straight road, passing two points A and B. At A the speed
of the car is 15 m s–1. When the driver passes A, he sees a warning sign W ahead of him,
120 m away. He immediately applies the brakes and the car decelerates with uniform
deceleration, reaching W with speed 5 m s–1. At W, the driver sees that the road is clear. He
then immediately accelerates the car with uniform acceleration for 16 s to reach a speed
of V m s–1 (V > 15). He then maintains the car at a constant speed of V m s–1. Moving at
this constant speed, the car passes B after a further 22 s.
(a) Sketch, in the space below, a speed-time graph to illustrate the motion of the car as it
moves from A to B.
When sketching these graphs, I am always having troubles distinguishing between the meaning of "for 16 seconds " and "further 22 seconds". If it says "for" does that mean that the time is for that particular block and if they say "further " does that mean that you add on the time from the end of the previous block.
I got the right answers but it was simply I guess due to chance. I feel i dont have the real understanding. "for " and further' is always getting me confused. HELPPPPPP>?
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'If it says "for" does that mean that the time is for that particular block and if they say "further " does that mean that you add on the time from the end of the previous block.'
Yes.
If you can hold your breath 'for' 2 minutes, it is understood that you start timing when the activity begins. Similarly "He ... accelerates ... for 16 s" means that this period of acceleration lasts for 16 seconds. The starting time is clearly given by "He then immediately...", indicating that it directly follows the previous section.
Similarly 'further' means 'extra, starting from where we already got to'.
Yes.
If you can hold your breath 'for' 2 minutes, it is understood that you start timing when the activity begins. Similarly "He ... accelerates ... for 16 s" means that this period of acceleration lasts for 16 seconds. The starting time is clearly given by "He then immediately...", indicating that it directly follows the previous section.
Similarly 'further' means 'extra, starting from where we already got to'.
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Your doubts are not reasonable because you are fully right. There are 3 periods of time here: decelerating that starts at point A and lasts to sign W, accelerating (from W to a certain point before B lets mark it as point M) and the period of constant speed that lasts 22 sec from M to B.
So accelerating lasts 16 sec. and further 22 s lasts driving at a constant speed.
So accelerating lasts 16 sec. and further 22 s lasts driving at a constant speed.
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get a math tutor?