# Physics

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#1
need help with this physics question
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4 weeks ago
#2
what's the question
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#3
(Original post by Isabel Steele)
what's the question
sorry completely forgot!
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4 weeks ago
#4
the first answer i thin is acceleration and the second = 3/20 = 0.15m/s
the reason that it is 4 irks is because you put down formula, working out, final answer and units.
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#5
(Original post by Isabel Steele)
the first answer i thin is acceleration and the second = 3/20 = 0.15m/s
the reason that it is 4 irks is because you put down formula, working out, final answer and units.
hi is that for the second part becuase i completelty forgot to say that it was the second question the 4 marker that i needed help on
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4 weeks ago
#6
hi is that for the second part becuase i completelty forgot to say that it was the second question the 4 marker that i needed help on
That is interesting because in my view, the first part of this question is conceptually more challenging than the second part. Whilst the question does not really make it explicitly clear whether it wants an instantaneous or average velocity, I think it is fine to calculate the average velocity. You already have the numbers from the graph to plug into the formula for speed, distance and time. Whilst it is not an issue here, be mindful of the units.
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4 weeks ago
#7
I don't think you can do 2.8/20, as the car is accelerating. s = d/t only works for constant speed. If they give you the acceleration, you could use the acceleration equation. If they tell you that the acceleration is constant, you could use a SUVAT formula. If they give you the equation of the curve, you could differentiate. If not, you could draw on a tangent to the curve when x = 20, and find the gradient of the curve, although this is less accurate.

Please correct me if you think that's wrong! But I'm pretty sure you can't just do s = d/t
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4 weeks ago
#8
(Original post by chipperpotato)
I don't think you can do 2.8/20, as the car is accelerating. s = d/t only works for constant speed. If they give you the acceleration, you could use the acceleration equation. If they tell you that the acceleration is constant, you could use a SUVAT formula. If they give you the equation of the curve, you could differentiate. If not, you could draw on a tangent to the curve when x = 20, and find the gradient of the curve, although this is less accurate.

Please correct me if you think that's wrong! But I'm pretty sure you can't just do s = d/t
You may be right, but I believe that would give you the instantaneous velocity. The average velocity could still be calculated using s = d/t. Unfortunately the question is not particularly clear either way.

However, you have actually made an excellent point in that the question may have given some additional information earlier on which the user has not provided us. I have only just spotted that this is parts four and five of Question 6!
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4 weeks ago
#9
(Original post by 0le)
You may be right, but I believe that would give you the instantaneous velocity. The average velocity could still be calculated using s = d/t. Unfortunately the question is not particularly clear either way.

However, you have actually made an excellent point in that the question may have given some additional information earlier on which the user has not provided us. I have only just spotted that this is parts four and five of Question 6!
Yes, I think there must be more information as this looks as if it is from an official exam paper and I think it's really unlikely that they wouldn't specify that they wanted average speed, if this is what they were looking for!
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#10
(Original post by chipperpotato)
Yes, I think there must be more information as this looks as if it is from an official exam paper and I think it's really unlikely that they wouldn't specify that they wanted average speed, if this is what they were looking for!
hi thanks for all your comments and help but this was on the 2021 additional assessment materials that aqa had released- the materials released are from past paper questions some from released papers and some unreleased and these are just bits - this is the whole question that i have given you if you would like to see for yourself here is the link for the materials - https://www.aqa.org.uk/2021-exam-cha...als#assessment go on to the bottom where it says get the support materials click gcse and physics and the paper is test 4 forces- higher
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4 weeks ago
#11
hi thanks for all your comments and help but this was on the 2021 additional assessment materials that aqa had released- the materials released are from past paper questions some from released papers and some unreleased and these are just bits - this is the whole question that i have given you if you would like to see for yourself here is the link for the materials - https://www.aqa.org.uk/2021-exam-cha...als#assessment go on to the bottom where it says get the support materials click gcse and physics and the paper is test 4 forces- higher
Hmmm that's very strange. Did they maybe take it from a longer question?

The only way to find the speed, or an estimate for the speed, would be to draw on a tangent. I don't know whether that's part of the AQA spec though!
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