Projectile Motion Problem Solving with Equations and Help from Experts

[Phunee]

Hi, I am having problems solving the last problem(see attached files), i have derived these equations which i thought should would help me solve the problem but i seem to be stuck.

U=(H3-H4)/(d4-D4)

Height at t

h and H3 are the same so i set H(initial)=0

-0,5gt^2+vsin(θ)t=-u*3*cos(θ)vt

Slope at t

-gt+vsin(θ)=uvcos(θ)

All help is appriciated

Anders.

 

[haruspex]

-0,5gt^2+vsin(θ)t=-u*3*cos(θ)vt
.

How do you get that equation? Why does it matter what the speed is after clicking (other than that it has enough impetus to break the window)?

 

[Ray Vickson]

Hi, I am having problems solving the last problem(see attached files), i have derived these equations which i thought should would help me solve the problem but i seem to be stuck.

U=(H3-H4)/(d4-D4)

Height at t

h and H3 are the same so i set H(initial)=0

-0,5gt^2+vsin(θ)t=-u*3*cos(θ)vt

Slope at t

-gt+vsin(θ)=uvcos(θ)

All help is appriciated

Anders.

Please do not post thumbnails; I could not read your solution on some media!

On the computer I am using now it is readable, but it is so simple you should have just typed it our directly. Read the 'pinned' thread 'Giudelines for students and helpers" by Vela, which discusses why thumbnails should be avoided if possible. (They are OK for things like diagrams from books and papers, etc., but should not be used for things like problem statements and/or written solutions.)