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# M1 Vectors Question watch

1. I've attached the question and the mark scheme. I understand everything except part d, the thing I'm most confused about is the 8/5 - I understand where the values come from but not why they're divided.

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2. (Original post by meloj)
I've attached the question and the mark scheme. I understand everything except part d, the thing I'm most confused about is the 8/5 - I understand where the values come from but not why they're divided.

Posted from TSR Mobile
If moves in the direction of then the velocity must be of the form

Now the magnitude of is but we need a magnitude of so we need to multiply the vector by

This works now since the magnitude of is .
3. since the direction of B is 3i+ 4j then a unit vector of velocity in that direction would be

{1/5}{3i+ 4j}.... this means the speed would be 1 m/s.

Since we want 8 m/s you multiply by 8

=====> {8/5}{3i+ 4j}
4. (Original post by notnek)
If moves in the direction of then the velocity must be of the form

Now the magnitude of is but we need a magnitude of so we need to multiply the vector by

This works now since the magnitude of is .
Thanks for your help! I understand it now
5. Thanks for your help! Much appreciated

(Original post by the bear)
since the direction of B is 3i+ 4j then a unit vector of velocity in that direction would be

{1/5}{3i+ 4j}.... this means the speed would be 1 m/s.

Since we want 8 m/s you multiply by 8

=====> {8/5}{3i+ 4j}

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