Projectile motion Questions (1 Viewer)

M@ster P

Member
Joined
Feb 9, 2008
Messages
619
Gender
Male
HSC
2009
Q1. A ball is projected so that its horizontal range is 45 metres and it passes through a point 22.5 m horizontally and 11.25 m vertically above the point of projection. Find the angle of projection and the speed of projection.

Q2. 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 collide.



Thx in advance.
 

nada92

Gotti Teiknadi <3
Joined
Apr 24, 2007
Messages
22
Gender
Female
HSC
2009
since it's a parabola, y=ax² + bx + c
c=0
therefore, y=ax² + bx
subbing in (45,0) ...
a=-b/45

then, subbing in (22.5,11.25) ...
11.25=506.25a + 22.5b

sub a=-b/45 into previous equation...
and you get b=1

therefore, y=-1/45 x² + x
differentiating, y'=-1/22.5x + 1
at x=0, m=1
therefore, tanΘ=1
Θ=45°

Now, to find velocity...
at full time of flight, x=(V²sin2Θ)/g
subbing in x=45, g=10 and Θ=45...
v=15root2 m/s

:) sorry about it being messy.
hope it helped!
EDIT: this is only Q.1
 
Last edited:

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top