Determining D traveled by xForce. (notschoolwork)

  • Thread starter Thread starter JesseIsAmazin
  • Start date Start date
AI Thread Summary
The discussion focuses on calculating the trajectory and force required to push a 4kg toolbox off one counter to land on another 2m away, with a height difference of 0.5m. The key equations for projectile motion are mentioned, including those for calculating initial velocity and displacement. The conversation highlights the importance of considering factors like the weight distribution of the toolbox and friction when determining the necessary force. Participants suggest starting with the initial velocity calculation while simplifying by ignoring air drag. Ultimately, the goal is to derive a formula for the force needed to achieve the desired landing position.
JesseIsAmazin
Messages
2
Reaction score
0
Not schoolwork but a question we have been looking at for awhile at work.


Homework Statement


Basically we want to know if I can push a rectangular toolbox thing off of 1 counter and have it land on another.

The box is 4kg
The height difference between the 2 shelves is .5m
Distance between the 2 is let's say 2m


Homework Equations



a = 9.8m/sec/sec
mass = 4kg
f = m x a
d = 2m

So basically I need to know how to determine the trajectory of the object at x force so I can determine how much force I need to use to move it to the desired final position. If I could find a formula that would let me say use 1Newton(i think that's what force is in) of force against it I could see where it would be after 2m of distance then just continue up until I reach the force I need to make it land on the other side (if its possible for me to even exert that much force.

The Attempt at a Solution



kinda tried on some paper but I don't know how to get the formula to figure out the trajectory because the object will be moving forward and dropping at the same time at different rates depending on the force and such. Any help? I am more then happy to spend some time working on it I just don't know where to start!
 
Physics news on Phys.org
That's kind of harsh, isn't it? You want to push the toolbox off one counter and have it land on another counter 2m away? Ouch. Bet it's not *your* toolbox!
 
Actually it was, and I broke it cause its plastic but duct tape is amazing and I fixed it. Sorta... but I "almost" made it, had I took the fact that the front half was lighter then the second half of the box and that it would and up hitting like /- instead of -_ like I hoped then I would have had it. But now that we all accepted that its possible I still want to figure out the equation for the amount of force needed to make it work.
 
You should start by calculating the initial velocity the toolbox should have when it just been pushed off the counter. I assume that the force applied is going to be horizontal only, so that means to say horizontal velocity of the toolbox in the air would be constant. You have the equations:

s=ut +1/2at^2
v^2 = u^2 + 2as
v = u+at

So with these you should be able to figure out the initial velocity of the toolbox. I'm ignoring factors such as drag in the air just to simplify matters here. Calculating the force needed is more difficult because you need to know the coefficient of dynamic and static friction as well as consider over what distance on the counter you would be pushing the box.
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top