Need help with projectile motion (1 Viewer)

[Smilebuffalo]

A particle is projected with a speed of 25m/s in the direction of a point P distant 24m horizontally and 7m vertically above the point of projection.
a) Find the coordinates of the point on the trajectory directly below P.
b) At the instant of projection of the particle, a second particle is dropped from P. Prove that the two particles will collide.

Full working out would be much appreciated. [answer for a) is (24,2)]

 

[gurmies]

Yfrog - 14974qc8.png
Yfrog - wowscrnshot060509191521h.jpg<!-- google_ad_section_end --></SPAN>

 

[addikaye03]

Yfrog - 14974qc8.png
Yfrog - wowscrnshot060509191521h.jpg<!-- google_ad_section_end --></SPAN>

Top shelf gurmies

 

[Smilebuffalo]

Hey gurmies. In part b) of the question you stated that for the second particle, when t = 1, y = 2.

How were you able to know this?




PS. I was also wondering how you were able to derive the vertical displacement of the particle P in terms of t.

 

[gurmies]

Well, I worked out y equation of the second particle to be y = -5t^2 + 7. When t = 1, y = 2

 

[Smilebuffalo]

ohhh cool cool.

I was also wondering when you find the y equation for the 2nd particle, what is the angle and velocity?

 

[gurmies]

Well, it's dropped - implying that there is no angle (i.e. no horizontal distance travelled). As for the velocity, due to the gravitational acceleration - it will be in terms of t (as it's not constant).

y: = -g

y. = -gt