Finding instantaneous velocity of objects in projectile motion

AI Thread Summary
To find the instantaneous velocity of an object in projectile motion at 3 seconds with no air resistance and an initial speed of 8 m/s, the components of displacement are given as dx=24 and dy=44. The vertical motion can be analyzed using the equation s=ut+(1/2)at^2, where the initial vertical velocity must be determined. Substituting t=3 seconds into this equation will yield the initial vertical velocity. The horizontal component of velocity can be calculated using v=d/t, confirming the overall velocity direction and magnitude. Proper application of kinematic equations is essential for accurate results in projectile motion analysis.
Suzan
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Homework Statement


No air resitance
Initial speed 8 m/s
inst. time at 3 s

Find instantaneous velocity at 3s.

Components of displacement:
dx= 24
dy= 44


Homework Equations



d=v1t+(1/2)a(t)^2 or other kinematics equations

The Attempt at a Solution



I tried to find the components of the velocity using the components of the displacement (d/t=v). But both my answer and angle of direction were wrong. How do i do this?
 
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Suzan said:

Homework Statement


No air resitance
Initial speed 8 m/s
inst. time at 3 s

Find instantaneous velocity at 3s.

Components of displacement:
dx= 24
dy= 44

So dx and dy are those values at t=3?
If so consider Vertical motion:
s=ut+\frac{1}{2}at^2

where u is the initial vertical velocity. Sub t=3 in there and get u. and well you know how to get the horizontal component (v=d/t as you stated before)
 
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