Finding instantaneous velocity of objects in projectile motion

[Suzan]

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?

 

[rock.freak667]

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)

 

[Moetasim]

I would first clarify the context of the problem. Is this a theoretical question or based on a real-world scenario? If it is a theoretical question, I would assume that the object is moving in a straight line without any external forces, and the initial velocity of 8 m/s is in the same direction as the displacement. In this case, the instantaneous velocity at 3 seconds would also be 8 m/s.

However, if this is based on a real-world scenario, I would need more information to accurately determine the instantaneous velocity. For example, the angle of direction and any external forces such as gravity or air resistance would need to be taken into account. In this case, I would use the kinematics equations to solve for the instantaneous velocity at 3 seconds.

To address the issue of your incorrect answer and angle of direction, I would suggest double-checking your calculations and making sure you are using the correct equations and units. It may also be helpful to draw a diagram or visualize the situation to better understand the components of velocity and displacement. If you are still having trouble, I recommend seeking assistance from your teacher or a tutor.