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looking for physics help

http://i.imgur.com/kIOe1wF.jpg
looking for help with the shopping cart question (the last question) - please try and NOT use calculus or any grade 12 concepts in this =)
willing to pay in cs go items
=DDDDD

February 26, 2015

10 Comments • Newest first

Ness

[quote=MrPickles]We know that the cart comes to a stop over some distance.
We also know that due to Newton's first law, the total force applied to the cart over the 12m distance must bring the carts velocity to 0 m/s.
If this condition is not met, the cart will either start moving backwards due to excessive force or continue moving east due to the lack of it.
Therefore, the cart's final position must be 12m

I have no idea how to prove this mathematically but this was the conclusion I came to after some thinking.
IF YOU FEEL LIKE MY LOGIC IS OFF, I IMPLORE YOU TO QUOTE ME SO I CAN FIX THIS AND LEARN FROM THIS. >.<[/quote]

Never mind, I can't read.

Yeah, you have a really bad question OP. You actually should complain to your professor.

Reply February 26, 2015 - edited
MrPickles

We know that the cart comes to a stop over some distance.
We also know that due to Newton's first law, the total force applied to the cart over the 12m distance must bring the carts velocity to 0 m/s.
If this condition is not met, the cart will either start moving backwards due to excessive force or continue moving east due to the lack of it.
Therefore, the cart's final position must be 12m

I have no idea how to prove this mathematically but this was the conclusion I came to after some thinking.
IF YOU FEEL LIKE MY LOGIC IS OFF, I IMPLORE YOU TO QUOTE ME SO I CAN FIX THIS AND LEARN FROM THIS. >.<

Edit: The math suggests that the shopping cart does not have a final position and that it will start moving west after 12m.

Since work (W) is equal to change kinetic energy (KE_change), the work done to get the cart to stop will be equal to 1/2 mv^2 = 121.5 J
However, since it is assumed that the applied force deceases steadily, i.e. uniformly, it would make sense that the equation for the applied for is F_a = 30-2.5x where x is the distance between 0 and 12m. Using the definition of work as an integral, we integrate F_a from 0 to 12m to get a value of -180J. Since I-180I > 121.5, it is implied that the cart will stop at some point, and start moving west to a position an infinite distance away.

Edit 2: This is all assuming that the applied force decays to 0N at the 12m mark. If this assumption is invalid, I assert that this problem is unsolvable since we do now know the rate of decay of the applied force.

Reply February 26, 2015 - edited
Ness

[quote=HolyDragon]The last question as in question 3?

30N over 12m
On a graph, start at 30 position 0 and draw a straight line to 0 at position 12.
The area of that graph is the total applied force (Fa).

Fa=Applied Force
Ff=Friction Force

Fa-Ff=m*a
Find the total acceleration to find the velocity at position 12

Afterwards
Ff=m*a
Use a
Velocity at position 12 is Vi here
Vf=0
vf^2=vi^2 +2ad

Please check the above formula, I may have recalled it wrong.[/quote]

There is no frictional force.

The problem is also worded badly. It states that the force decreases steadily until the cart hits 12m. The problem doesn't state that the force [b]decreases to zero[/b], meaning that the cart would have a non-zero net velocity unless the force reduced its velocity to zero.

Reply February 26, 2015 - edited
HolyDragon

The last question as in question 3?

Edit: The guy below has indicated that I misread. Fixing

30N over 12m
On a graph, start at 30 position 0 and draw a straight line to Y at position 12.
The area of that graph is the total applied force (Fa).

Fa=Applied Force

-Fa=m*a

It has to have enough force that it stops at position 12
Rectangle + Triangle=ma

(Y*12)+(30-Y)6=ma

Might've messed up some signs somewhere.

Reply February 26, 2015 - edited
PwNpWnPwN

its probably on google... just google it.

Reply February 26, 2015 - edited
DeprivedChild

How's after school, it's easy but cbf writing it on basil in class

Reply February 26, 2015 - edited
iHartz

[quote=DeprivedChild]@iHartz: when do you need the help[/quote]

like right now

Reply February 26, 2015 - edited
iHartz

[quote=DeprivedChild]First up what cs thing can you pay[/quote]

p250 cartel ft

Reply February 26, 2015 - edited
DeprivedChild

First up what cs thing can you pay

Reply February 26, 2015 - edited