Question

Force and Motion: A 12 kg armadillo runs onto a large pond of level, frictionless ice. The armadillo's initial velocity is 5m/s along the positive direction of the x-axis. Take its initial position on the ice as being the origin. It slips over the ice while being pushed by a wind with a force of 17N in the positive direction of the y-axis. In unit vector notation, what are the animal's (a) velocity and (b) position vector when it has slid for 3 seconds?

Answer 1

There is no force in the x direction so the x velocity, call it u, remains constant at 5 m/s.
There is an acceleration, 17/12 m/s^2 in the y direction
The initial y velocity, call it Vi, is 0
so
v = Vi + a t
v = 0 + (17/12)(3)

the velocity vector at 3 seconds is therefore
V = 5 i + (17/4) j

the position in x is 5 *3 = 15 meters
the position in y is
y = (1/2) a t^2 = (1/2)(17/12)(9)
so
position vector = 15 i +(17*3/8)j