Recent content by BarneyStinson

We were never given an explanation in class. I remember in my high school physics class last year, our teacher told us this is true but never showed us why. All he said was that you had to integrate a function relating distance to mass, and the result would be a net force of 0 anywhere inside...

This isn't a homework question. I just saw 2012 and it bugged me when they made a turn and stayed in the car with an open door. i calculated the centripetal force to be 12,000 N. I assumed a mass of 90 kg. The mom had no seat belt and was holding on to a child. Could she have stayed seated or...

Yeah, he is. I just don't like how he said "Be very careful when you draw the free body for the whole box". He made it out to be crazy hard.

That would be 1029N. Fun=140(7.35) That looks too simple. Our teacher said this is a very difficult problem...

I drew a better diagram, because i now know what i did is wrong. The acceleration is 7.35m/s^2. I do not know where to go from here. I know Joe has to apply a force on the cube. I know that Brian (the hanging one) will accelerate in the same direction as the applied force. I don't know...

Homework Statement John (mass 80) rests on top of a light cube (mass = 0). A light rope passes horizontally from him over the front edge, and vertically down to Brian (mass 60kg) who hangs in contact with the front face as shown. The cube is on a horizontal surface and there is no friction...

Homework Statement A rock is thrown from the top of a slope that makes an angle of 30 degrees with the horizontal. At what angle to the horizontal should the rock be thrown to get a maximum range? (Hint: pick the direction of the slope as a new x-axis and the normal to the slope as the new y...

Since my teacher never gave us the equation for height i posted above, he said we have to derive it ourselves... I have no idea how to do this, can you guys help me out? And i still don't understand how to derive the equation R=h/4

Ok, i found it. I used the wrong equation for height. This is the right one: http://upload.wikimedia.org/math/9/7/e/97e83759703c5fa053baed5f06c1dfa7.png I still don't understand the second part though.

Homework Statement Show that the range R can be expressed in terms of maximum height h, and in particular that R=4hcot\Theta. Show that, when range is at a maximum, h=R/4 Homework Equations R=(v(o)^2*2sin\Thetacos\Theta)/g v(y)^2=v(yo)^2-2gh The Attempt at a Solution I used the second...