This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Quiet please ladies and gentlemen The lecture is about to begin n M A box of mass M = 10 kg slides down a frictionless wedge with angle of incline θ = 30°. At the base of the wedge the box collides with a spring which compresses 10cm before the box stops moving, if the total distance the box slides is d = 2m . Q. What is the spring constant? Given: • M = 10kg • θ = 30° • d = 2m • x = 10cm Find: • k = ? θ ( 29 ( 29 g S g S i f KE PE PE KE PE PE + + = + + P E mgh = K E = 2 1 2 PS E kx = Initial state Final state K E = PS E = P E = 2 1 2 mgh kx = 2 2 mgh k x = ( 29 sin h d θ = ( 29 2 2 sin mgd k x θ = ( 29 ( 29 2 2 10 9.8 2sin 30 19600 0.1 N k m × × × ° = = h 2 d m = x Conservative systems with springs 2 y m F mg n R υ = + = ∑ A rollercoaster slides down from rest at A on a frictionless track. The radius of the curved path is R. Q. What is the minimum height h required, so that it does not does not fall at point B? h R Conservation of energy: problem solving ( 29 ( 29 B A KE PE KE PE + = + A PE mgh = 2 1 2 KE m υ = A: B: KE = 2 PE mg R = 2 1 2 2 m mg R mgh υ + = 2 m mg R υ = 2 gR υ = 1 2 2 gR g R gh + = 5 2 h R = B mg n +ve n = Friction • If you pull a sled to the top of a hill and there is friction between the sled and the ground, and you expend the...
View
Full Document
 Fall '07
 Dr.Jackman
 Physics, Energy, Force, Friction, Mass, Potential Energy, Wext, mg cos

Click to edit the document details