<p>1.) A crate weighing 1000N is pushed up an inclined plane a distance of 20 m. The plane makes an angle of 30 degrees with the horizontal and the crate moves with constant velocity for 2 seconds. If the coefficient of friction between the crate and the inclined plane is 0.25, how much power is expended in pushing the crate?</p>
<p>2.) How long will it take a 20000N SUV to accelerate from rest to 60 mph if the car has a 280 horsepower engine? (1 hp = 746 watts)</p>
<p>I think for number 1 this is how u do it:
F(f)=(mu) x F(n)
F(n)=Fgcos(35)
F-F(n)cos(35)-F(f)=ma=0
the rest is plug in</p>
<p>BTW what book you recoment for SAT Physics? princeton any good?</p>
<p>2.) How long will it take a 20000N SUV to accelerate from rest to 60 mph if the car has a 280 horsepower engine? (1 hp = 746 watts)</p>
<p>If the car weighs 20,000 N, find the mass of the car (divide by 10). The car initially had no kinetic energy, but after a certain period of time the kinetic energy is (.5)(mass)(velocitysquared).
Remember to change the velocity into meters per second.</p>
<p>Then, Power = Energy/t</p>
<p>Convert horsepowers into watts.</p>
<p>Amount of watts= Kinetic Energy / time.</p>
<p>You have the amount of watts and the amount of energy (kinetic energy), substitute and solve.</p>
<p>I think ...</p>
<p>About the books, from what I've heard the absolutely best plan is to start with Princeton and if you can, pass on to Barron's which is harder than the actual test. I've heard the Princeton is really similar to the actual test, I took the December test and did not find Princeton to be very similar. However, Princeton really helped me to understand the concepts of the test.</p>
<p>Yea, I agree with the Princeton book, which I personally used. I'd avoid Barron's though; there have been many horror stories of confusion with the material (Barron's made it much harder than the actual test) and mistakes in the book.</p>