# Kinematics Help

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#1
Can someone help me with this question please, I just keep getting it wrong!In this question, i and j are the standard unit vectors in the Ox and Oy directions.An object has initial position (2i – j) m and velocity (-i 4j) ms-1It has a constant acceleration of (2i 5j) ms-2Calculate the object’s velocity and position after four seconds.
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1 month ago
#2
(Original post by millieahx)
Can someone help me with this question please, I just keep getting it wrong!In this question, i and j are the standard unit vectors in the Ox and Oy directions.An object has initial position (2i – j) m and velocity (-i 4j) ms-1It has a constant acceleration of (2i 5j) ms-2Calculate the object’s velocity and position after four seconds.
What have you done? Since you're getting it wrong you must have something to show us.
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#3
(Original post by Plücker)
What have you done? Since you're getting it wrong you must have something to show us.
sure. I've figured out how to get v, which I used the v=u+at formula for: v=-1i+4j+4(2i+5j) which equals 7i+24j. However when I try to work out r I get 12i+56j. I put it into the r=ut+1/2at^2 formula to get this, but that's not the answer.
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1 month ago
#4
(Original post by millieahx)
sure. I've figured out how to get v, which I used the v=u+at formula for: v=-1i+4j+4(2i+5j) which equals 7i+24j. However when I try to work out r I get 12i+56j. I put it into the r=ut+1/2at^2 formula to get this, but that's not the answer.
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