# 12U Physics - Motion and Dynamics! Please Help!

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• Mar 24th 2008, 07:30 PM
xkissesx
12U Physics - Motion and Dynamics! Please Help!
This is an assignment from my physics class that counts for 1/3 of my midterm mark. It's suppose to be basic ... I think .. but I just don't know where to start.
Here's the question Illustrated
http://i284.photobucket.com/albums/l...8/untitled.jpg
A pulley device is used to hurl projectiles from a ramp (kinetic friction = 0.26) The 5.0 kg mass is accelerated from rest at bottom of 4.0m long ramp by a falling 20.0kg mass suspended over frictionless pulley. Just as the 5.0 kg mass reached the top of the ramp it detached from the rope (neglecting mass of the rope) and becomes projected off the ramp. Determine the horizontal range of the 5.0 kg mass from the base of the ramp.
Anything will help, even guesses.
• Mar 24th 2008, 09:22 PM
o_O
Looking at the 5.0 kg block, the net force acting on it along the incline includes friction, gravity ( $mgsin\theta$), and the tension of the rope. Each of these can be calculated and thus, you can find the acceleration of the block ( $F_{net} = ma$).

Now, use your kinematics equations to determine what it's velocity is by the time it reaches the top of the ramp (you're given that it's 4.0 m) and note that it will be 'launched' at a 30 degree angle. You should be able to determine how far it will land with all this in mind. Keep in mind that once the 5.0kg is released, it will not be accelerating (at least, that is what is presumed).