# Homework Help: Questions in [ motion in two dimensions ]

1. Oct 21, 2009

### mo3az

questions in [ motion in two dimensions ]

q. [ .. if you know the position vectors of a particle at two points along its path and also know the time interval during which it moved from one point to the other m can you determine the particle's instananeous velocity ? its average velocity ? Explain.

q. [.. a projectile is launched at some angle to the horizontal with some initial speed vi and air resistance is negligible . is the projectile a freely falling body ? what is its acceleration in the vertical direction ? what is its acceleration in the horizontal direction ?

q. [ ..O stat which of the following quantities , if any , remain constant as a projectile moves through its parabolic trajectory :(a) speed (b) acceleration (c) horizontal compnent of velocity (d) vertical component of velocity .

2. Oct 21, 2009

### superdave

1) Instantaneous velocity is it's velocity at any given point right at that instant. Average is it's velocity over some distance for some amount of time.

2) If you throw a ball, after you throw it, what forces are acting on it? And what direction do those forces pull? there is no acceleration without a force.

3) You need to look at each of those quantities and think about what happens to a ball when thrown. Remember, after the ball leaves your hand, only certain forces are working on it. Acceleration will only change due to a force. Velocity will only change due to an acceleration.

3. Oct 21, 2009

### mo3az

Thank u alot ,,