<p>I got a few SAT Physics problems from my teacher and I do not understand them at all! </p>
<ol>
<li><p>In 1994, A Bulgarian athlete named Minchev lifted a mass of 157.5 kg. By comparison, his mass was only 54 kg. Calculate the force acting on each of his feet at the moment he was lifting the mass with an upward accleration of 1 m/s^2. Assume that the downward force on each foot is the same.</p></li>
<li><p>In 1967, one of the high school football teams in California had a tackle
named Bob whose mass was 2.20 </p></li>
</ol>
<p>bump
no replies? -_-</p>
<p>10 char</p>
<p>Well, let’s see.</p>
<p>For the first:</p>
<p>F = m*a
Don’t forget that gravity is also acceleration which is always there !</p>
<p>We have two forces here, first he’s body weight and then the weight he is lifting.
His body: F = 54*10 = 540
The lifted weight: F = 157.5 * 11 = 1732.5 (add gravity and lifting acc.)
In total, this gives us 2272.5 N, or 1136.25 N for one foot.</p>
<p>Not sure why you have 1116 N, but my calculations seem to be correct.</p>
<p>Second:</p>
<p>Well, again F = m<em>a
I’ll assume that 2.20 * 102 actually means 2.2 * 10^2. We then get F = 220 * 75 = 1.65</em>10^4. Additionally, you need to add normal gravitation, so F = 220 * 85, yielding a total of 1.87 * 10^4</p>
<p>You can do the third using simple trigonometric functions - just split each force into a vertical and a horizontal part, add all of them, use tan to calculate a new angle and pythagoras to calculate the magnitude. I won’t do that now because it’s boring.
For b, simply divide the force by the balloons mass.
For c, you’ve got a right triangle:
A
|\
| \
| \
| \
C----B
Where angle A is 90 - the angle of the force you calculated for step a) and length of side B is 45m, since you want to bring the balloon down to the ground. Then, use tan(angle A)<em>b to calculate side a. (ie tan(90-41)</em>45=tan(49)*45=51.77</p>
<p>Firstly, Welcome to CC! I hope we can help you as much as you’ve helped us! 
Thanks so much!</p>
<p>For the first one; however, I have a question, why would you add the acceleration of gravity and the acceleration applied by the athlete lifting are in opposite directions?</p>
<p>Thanks for the explanations :D</p>
<p>Also, i have one last problem I was stuck on.</p>
<p>The largest squash ever grown had a mass of 409 kg. Suppose you want
to push a squash with this mass up a smooth ramp that is 6.00 m long
and that makes a 30.0° angle with the horizontal. If you push the
squash with a force of 2080 N up the incline, what is
a. the net force exerted on the squash?
b. the net acceleration of the squash?
c. the time required for the squash to reach the top of the ramp?</p>
<p>The answers should be:
a. 70 N at 30.0° above the horizontal
b. 0.2 m/s2 at 30.0° above the horizontal
c. 8 s</p>
<p>Again, Thanks so much! I really appreciate it! If you don’t mind me asking, what are you looking for on CC? Maybe I can help you :D</p>
<p>I’m not home now, but regarding the first: from the point of view of the weight, 11m/s^2 acc. is in effect. (grav + lifting, just as you feel heavier if you are acc upward) Since every force has an equal force into the opposite direction, this force also acts on the feet of the lifter. </p>
<p>My short term goal is to get 800 on the math II and the physics SAT, but ultimately I’d like to get into MIT ^^
(I’m an international student btw, so I’ll probably study at home if I don’t get into MIT)</p>
<p>Oh ok that makes sense, thanks. </p>
<p>Oh, you seem really good at physics so that shouldn’t be too hard for you. My teacher hasn’t exactly taught this to us, yet he decided to assign it over our fall break -_- Oh, which country are you from? Have you taken the SAT yet?</p>
<p>Just buy a SAT prep book, most of them contain all the information you need. (I’ve got the Barrons for Math and Princeton review for physics)</p>
<p>Actually I’m from Austria, so English isn’t my native language. Got 800 on Critical Reading and Math though 
Sadly only 690 on Writing, but hopefully I’ll get 800 there on my second try. ^^</p>
<p>Haha yeah I have them, but I’m only about 1 and a half months into my Honors physics class, so yeah it’s frustrating at times! </p>
<p>That’s an awesome score! I hope I can get my CR to 800, its around 700. My Math is usually 800 and writing is 750+
For your writing, definitely check out: <a href=“http://talk.collegeconfidential.com/sat-preparation/955109-silverturtles-guide-sat-admissions-success.html[/url]”>http://talk.collegeconfidential.com/sat-preparation/955109-silverturtles-guide-sat-admissions-success.html</a></p>
<p>It helped me bring my 620 writing to a consisten 750+. I’m in 10th grade, btw, what about u?</p>
<p>Thanks, for that link, I’ll check it out. I already finished highschool - currently, I’m doing my mandatory period of community service. >.< (and a bit of it consulting to save
up some money)</p>
<p>Most of the time, those SAT books are enough to prepare you though, so you can use them to find the solutions for your exercises.</p>
<p>Thanks again for all the help!</p>
<p>Hope you’re successful in all your pursuits!</p>