Quick Question

[Lols123]

Just wondering about this question why the acceleration down the incline (mass x 80gsin33.67 x 15 ) isnt included in the work calculation

[Milkshake]

Where did u get 33.67 degrees from?
And is the work done 11000J?

[davidle_10]

the angle i got was sin-1(10/15)=41.8 degress
And yep I worked it out to be 11kj as well

[Lols123]

oops yeah the angle is 42 degrees
yeah 11,000 is the answer
did you guys use the acceleration down the incline? (mass x 80gsin41* x 15)

[xZero]

w=fx, this question is pretty badly worded, it didn't specify that he only puts enough force to keep the netforce = 0. Anyways acceleration is not required in this case as you use w=fx where f=|all resistance forces|

[Bozo]

Wait so because there is 0 acceleration, you can just straight out apply W=F.x

[xZero]

basically, to maintain the 0 netforce you must put in f amount of force which equals to all resistance forces. Then work=fx where f=the force you're putting into the system. with acceleration, say 10ms^-1, use fnet=ma, work out the amount of force required to achieve that net force and sub it into work=fx

[ttn]

Another way is:

Finding the work done due to friction
and add
work done against gravity to get to that height (don't know what it's actually called)

so W = F(friction)x + mgh

= 200*15 + 80*10*10
= 3000+8000
= 11000J

[Allygator]

what exam is this from?