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# M2 Kinematics watch

1. When a vector is parallel to the (i-j) vector I tried to put the i part minus the j part and then equate everything to 0. This results in a wrong answer and I don't understand why..
Like looking at the ms/solution it equates the i part to the NEGATIVE j part. Why is that?
2. (Original post by RK1998)
When a vector is parallel to the (i-j) vector I tried to put the i part minus the j part and then equate everything to 0. This results in a wrong answer and I don't understand why..
Like looking at the ms/solution it equates the i part to the NEGATIVE j part. Why is that?
3. (Original post by TeeEm)
a= (5t-3)i + (8-t)j ms**

when t=0, v=(2i-5j) ms*

a) velocity after t seconds is (2.5t^2 -3t +2)i + (8t-0.5t^2 -5)j

b) Find the value of t for which is moving parallel to i-j

c) Find the speed when it is moving parallel to i-j

# I need help with part b please #
4. (Original post by RK1998)
a= (5t-3)i + (8-t)j ms**

when t=0, v=(2i-5j) ms*

a) velocity after t seconds is (2.5t^2 -3t +2)i + (8t-0.5t^2 -5)j

b) Find the value of t for which is moving parallel to i-j

c) Find the speed when it is moving parallel to i-j

# I need help with part b please #
When it's moving parallel to i - j, the general velocity vector will be equal to some constant multiplied by the vector I - j.
5. (Original post by RK1998)
Yeah but does this mean that I equate to 0 the velocity of i+j or i-j ?
When P moving parallel to it means that .

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