### Help with physics?

First Riot Post

Best Robot EU

Senior Member

Quote:
Originally Posted by YGY818
Phone a friend. (classmate)
I don't have any irl friends

Father Zyzz

Member

Quote:
Originally Posted by Best Robot EU
f=ma?
Yay!
We are missing the acceleration of the boat but are given the tools to find it. Give an attempt, friend.

Best Robot EU

Senior Member

Quote:
Originally Posted by Riot Morgageddon
Morgageddon tries to remember college...

Well, it's worded awkwardly, but I have to assume you go from 3 m/s at the start of your 500m and then end at 16 m/s at the end of the 500m. From this, you can make a velocity profile, use the standard kinematic equation and integrate to find the total energy expended to have the sailboat go from 3 m/s to 16 m/s over 500 meters. Then, you can equate that to an equal force applied at a single point at the start, with a magnitude and a direction, something that'll be like 1500N @ 73 degrees north of east (since you said nothing about currents or other forces acting on the sail boat).

tl;dr

Draw out the problem to start. Find your governing equations. Solve said equations.
oh
um
ok
ty morgageddon

Spitsonkittens

Senior Member

LOL. Morgageddon responds to help. What a nice guy.

Still ironic that instead of moving to off-topic he helps. Oh GD...

Desmond Law

Senior Member

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His ship destroyed, his crew nowhere to be found, Olaf miraculously washed up untold miles from "friendly" waters on the foreign shores of Valoran, south of Demacia. This unfamiliar place stunned and frightened the Berserker, for Lokfar is not privy to such potent magicians. Approaching them, Olaf hoped that they could use their mysterious powers to send him back to his people. A bargain was struck. Olaf would use his awesome prowess as a warrior to serve the unusual wars of Valoran in the League of Legends, and in exchange the sorcerers would find him a way to return. Despite his participation in the League, Olaf knows better than to trust the "finger wagglers" that run the Institute of War. He deliberately keeps details of his life and home from them. After all, with enough information, they would most certainly find the Lokfarians and dominate them as they have dominated all of Valoran, keeping both quietly – and unwittingly – in their thrall.

Riot Morgageddon

Player Support Tech Specialist

Morgageddon thinks to his engineering books back in his apartment.

LOL. Morgageddon responds to help. What a nice guy.

Still ironic that instead of moving to off-topic he helps. Oh GD...

I did graduate with a BS in Mechanical Engineering, this kind of stuff brings back memories of college and problem solving

Best Robot EU

Senior Member

woot i got it
ty everyone

Samflash3

Senior Member

Quote:
Originally Posted by Best Robot EU
woot i got it
ty everyone
Did you use the equations of motion?

Flennel

Senior Member

Quote:
Originally Posted by Best Robot EU
A 380 kg sailboat increases its speed from 3 m/s to 16 m/s while travelling 500 m at an angle of 73° north of east. Find the magnitude and direction of the net force that acts on the sailboat.

holy **** how do I even do this
First of all, this feels trolly. Especially, knowing your post history in GD.

The 73 degrees does not matter unless the problem specifically says to break down the forces to North (a Y) and East (as X) coordinate system.

Assuming the acceleration is uniform, then 500 meters is travelled on average of (3+16)/2=9.5 m/s speed over 500 meters. 500/9.5 = 52.63 seconds. Acceleration therefore is dv/s = (16-3)/(500/((3+16)/2)) = (16-3)(16+3)/(500*2) = 256-9/1000 = 0.247.

So F=380*0.247 = 93.86

Daedalus871

Senior Member

F = ma

(V^2(final)-V^2(initial))/2 = a*(distance traveled)

North of East implies that it is rotated counterclockwise 73 degrees from the x axis (East),

F(x) = Fcos(73), F(y) = Fsin(73) (from the geometry of the problem)

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