Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    16
    ReputationRep:
    Hi can someone please explain how the answer to question 20 is C and not D. I can't seem to get 25m please help😣😣😣Name:  ImageUploadedByStudent Room1465142641.675963.jpg
Views: 75
Size:  144.0 KB


    Posted from TSR Mobile
    Offline

    1
    ReputationRep:
    The question is asking for the distance travelled in only the third second. Your calculations have worked out the distance travelled in three consecutive seconds, so you need to subtract the distance travelled in two seconds from that to get the distance travelled in just the third second.

    45= 0*3 + 0.5*10*3^2
    20=0*2 + 0.5*10*2^2

    45-20=25
    Offline

    3
    ReputationRep:
    (Original post by LittleBoxes)
    Hi can someone please explain how the answer to question 20 is C and not D. I can't seem to get 25m please help😣😣😣Name:  ImageUploadedByStudent Room1465142641.675963.jpg
Views: 75
Size:  144.0 KB


    Posted from TSR Mobile
    Hello there,

    When faced with a question like this, I find it useful to draw a quick sketch of the velocity-time graph for this situation. This allows for me to easily visualise the nature of the question. Below, I have added an accurate plot (the sketch doesn't need to be this accurate, of course).
    Name:  v-t.PNG
Views: 16
Size:  6.7 KB
    Here, I have shaded the area that represents the displacement that the question is asking for. As we know the equation of the line (v = 10t), we can calculate the value of  v at  t = 2 s and  t = 3 s. Once we haves those, we can calculate the displacement by calculating the area of the trapezium.

    I hope that this has been helpful.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What's your favourite Christmas sweets?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.