Question

Kinematics qn

Answer 1

Can you draw a picture?

Answer 2

is that correct?

Answer 3

Almost - there are few things that need to be corrected. If y is pointing across the river, and x is pointing downstream:

first, the x velocity component of swimming is
1.5 cos A
and with the angle as you've drawn it, points in the direction of water flow (to the right) and is thus added, so the total x velocity would be

Vx = 2.5 + 1.5 cos A

Similarly for Vy, it points towards the top of the picture, so would be

Vy = 1.5 sin A

Answer 4

Oh, that makes sense, haha, how do i draw it to make my statement correct?

Answer 5

anw, since the qn is asking for the direction im not really sure hwo to answer this..

Answer 6

bt i think we need to find the angle, but the equation alone is insufficient

Answer 7

Luckily we can logic our way through finding the angle! The question doesn't ask to minimize anything but the amount of time it takes to get across the river.

Each velocity acts independent of the other - so if there were no current, what's the fastest way the person can swim across the river?

Answer 8

~~ each *component* of the velocity acts independent of the other

Answer 9

hmm.. no current, then just walk across? fastest time will be t=80/1.5sinA then?

Answer 10

And what would A be?