Physics Help -- PLEEEASE!!

R.D

Ok, I'm really weak when it comes to Physics but have to do it in my course -- studying Applied Bioscience. Spent the last two hours on this one question which is supposed to be handed in tomorrow along with several others as part of my continous assessment. I already posted this in the Physics forum but the chances of someone answering it by tonight are slim so it'd rock of one of you guys could help a veteran of this forum out haha! Here's the question...

An object of mass 200kg initially moving along a horizontal surface with a velocity of 15 ms-1 is brought to rest by a frictional force of 600 N.

Calculate :
(a) the deceleration
(b) the distance travelled
(c) coefficient of friction
(d) the work done in bringing it to rest.

If I could just calculate the deceleration I'm sure I could manage the rest, it's just I'm not sure how to go about finding the deceleration because of the lack of info in the question.

So far I think I've to take gravity into consideration and use the formula 'v= u + gt' to get the time, but then what -- do I use that 't' value to get the acceleration in the formula 'v = u + at', man I'm so confused. Any help would be very much appreciated!!

rjt

F=ma
So 600=(200)a
a=3 m/s^2

So the de-accel is 3.

Limerick Dude

I hate physics, oh so much

JC 2K3

(a)
F=ma
-600=200(a)
a= -3ms^-2

ie. deceleration is 3 ms^-2

(b)

v^2 = u^2 + 2as
0 = 15^2 + 2(-3)s
s = 15^2/6
s = 37.5m

(c)

Mu = Fr/R
R = 200g
Fr = 600N
600/200g = 3/g (= 3/9.8)

(d)

W = Fs
W = 600(37.5)
W = 22500J

I think that's all right. I was bored so I did the whole thing.

madgal

I love physics. If your ever unsure about exam questions, i sneakly found this the other night. Go into Examinations.ie and click on marking scheme, and click on the subject. It brings up the questions, the answers, how much marks you get for saying what, and what they dock marks for. Its brilliant if you have a wick teacher who 'forgets' to tell you what you get the marks for.

unnameduser

Just a quick note:
It is a good idea to study the marking schemes to get a full understanding of how the marks are awarded. This will help you construct your answers with in the intent on getting the maximum number of marks - However, do not fall into the habit of looking at the marking schemes for every answer. It is imperative that you create the answer yourself rather than finding it in the marking schemes. Go look for the answers in your notes or book. Best of luck with your study.

ninebeanrows

Jewels wrote:

Hi if you need help with your physics have a look at www.examsupport.ie they cover the entire physics syllabus and a lot of the modules come complete with experiments! They also include a section on past exams and go through typical exam questions.

Yea only found that link a few days ago, very very good... With such an imcompetant teacher as mine is, i need all the resources i can find... Our class hardly knows what the structure of the paper is... i say hardly i should use the word doesn't :mad: