Question

8. A big metal bead slides due to gravity along an upright friction-free wire. It starts from rest at the top of the wire, Point A, as shown in the sketch. How fast is it traveling as it passes Point B?- Point D?- Point E? Maximum speed occurs at Point 5 m 9. Rows of wind-powered generators are used in various windy locations to generate electric power. Does the power generated affect the speed of the wind? That is, would locations behind the "windmills" be windier if windmills weren't there? Discuss this in terms of energy conservation with your classmates.

Answer 1

Use work energy theorem to find the speed at the given point as shown below. Maximum speed occurs at a point where potential energy would be minimum.

8) a) from work energy theorem, from A to B - Wgravity = AKE sme mass = mgh = / m(W3² - VÅ) { n=sm - gh = ² (VB²-o) =) VB = √2gh = 52x9.8*5 m/s = [9.9 m/s Since D and EE are at same level as B, his same for D and E and hence speed is, Vo = VB = 19.9 m/s VE = VB = 19.9mis b) Max. speed occurs at point c, because potential energy will be lowest at c.