angular and linear speed & find angel of elevation

Geometric formulae, word problems, theorems and proofs, etc.
maria1983
Posts: 8
Joined: Sat Mar 07, 2009 10:00 pm

angular and linear speed & find angel of elevation

1. A wheel has a radius of 14 feet. The wheel is rotating at 21 revolutions per minute. Find the angular and linear speed. Leave your answer in terms of "pi".

what is angular and linear speed?

2. A guy wire fifty feet long is attached to the top of a pole forty feet tall. THe wire is also attached to the ground at a point thirty feet from the base of the pole. Find the angle of elevation. Round your answer to two decimal places.

i did a picutre but what next?

stapel_eliz
Posts: 1628
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
1. A wheel has a radius of 14 feet. The wheel is rotating at 21 revolutions per minute. Find the angular and linear speed. Leave your answer in terms of "pi".

what is angular and linear speed?
"Angular speed" should be defined in your book. There is more than one definition. But since "21 revolutions per minute" is given in the exercise, that's probably not what they want. Maybe "radians per minute", with one rotation being $2\pi$ radians...?

"Linear speed" is the distance you'd cover on the ground if the wheel were rolling down the road. You find the circumference (using $C\, =\, 2\pi r$) and then multiply by the number of times that circumference has spun around.
2. A guy wire fifty feet long is attached to the top of a pole forty feet tall. THe wire is also attached to the ground at a point thirty feet from the base of the pole. Find the angle of elevation. Round your answer to two decimal places.

i did a picutre but what next?
Use one of the trig ratios for a right triangle. Once you've set up the ratio, use the "inverse (whatever trig function you've chosen)" button on your calculator to find the angle measure.

Make sure the calculator is in "degree" mode!

maria1983
Posts: 8
Joined: Sat Mar 07, 2009 10:00 pm

Re: angular and linear speed & find angel of elevation

2. A guy wire fifty feet long is attached to the top of a pole forty feet tall. THe wire is also attached to the ground at a point thirty feet from the base of the pole. Find the angle of elevation. Round your answer to two decimal places. i did a picutre but what next?
Use one of the trig ratios for a right triangle. Once you've set up the ratio, use the "inverse (whatever trig function you've chosen)" button on your calculator to find the angle measure. Make sure the calculator is in "degree" mode!
i did sin(angle)=40/50 then i did sin-1 on 40/50 i got 53.13010235 is this rite?

stapel_eliz
Posts: 1628
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
i did sin(angle)=40/50 then i did sin-1 on 40/50 i got 53.13010235 is this rite?
Remember to label (with the "degree" symbol), and to round to the specified number of decimal places.