Can anyone help me with these problems? Thank-you(adsbygoogle = window.adsbygoogle || []).push({});

1.) In a circus performance, a large 4.0 kg hoop with a radius of 1.8 m rolls without slipping. If the hoop is given an angular speed of 5.0 rad/s while rolling on the horizontal and is allowed to roll up a ramp inclined at 12° with the horizontal, how far (measured along the incline) does the hoop roll?

I know I have to use the total mechanical energy formula to solve for the height, then find the sin of 12°. I tried canceling out, and not but each answer I got was wrong. So It would be 1/2mv²+1/2mr²(v²/r²)=mgh, which is 1/2(4)(5²)+1/2(4)(1.8²)(5²/1.8²)=(4)(9.8) when I canceled out I got 50=39.2h (h=1.28), when I did not I got 100=39.2h (h=2.55). After that, I solved for H, with sin12=oppositite/hypotenuse, so I got H=-2.38 and -4.75. I know that distance can't be negative, so I'm pretty sure my signs aren't my problem.

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2.) A mechanic jacks up a car to an angle of 8.0° to change the front tires. The car is 3.20 m long and has a mass of 1160 kg. Its center of mass is located 1.12 m from the front end. The rear wheels are 0.40 m from the back end. Calculate the torque exerted by the car around the back wheels.

I know it's going to be negative, and that Torque= Fr sin theta

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# Homework Help: Rotationl Equilibrium Help

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