Homework 10

# Homework 10 - Gozick Brandon – Homework 10 – Due 5:00...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Gozick, Brandon – Homework 10 – Due: Oct 13 2006, 5:00 pm – Inst: D Weathers 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 2) 10 points At time t i , the kinetic energy of a particle is 15 . 6 J and its potential energy is 5 . 18 J. At some later time t f , its kinetic energy is 27 . 8 J. If only conservative forces act on the parti- cle, what is its potential energy t f ? Correct answer:- 7 . 02 J. Explanation: From conservation of energy U i + K i = U f + K f , we obtain U f = K i + U i- K f = (15 . 6 J) + (5 . 18 J)- (27 . 8 J) =- 7 . 02 J . 002 (part 2 of 2) 10 points If the potential energy at time t f is 6 . 22 J, what is the work done by the nonconservative forces acting on the particle? Correct answer: 13 . 24 J. Explanation: The work done by the nonconservative forces is W = Δ K + Δ U = [(27 . 8 J)- (15 . 6 J)] + [(6 . 22 J)- (5 . 18 J)] = 13 . 24 J . keywords: 003 (part 1 of 2) 10 points A single conservative force acting on a particle varies as ~ F = (- Ax + B x 2 )ˆ ı, where A = 11 N / m and B = 12 N / m 2 and x is in meters. Find the change in potential energy as the particle moves from x = 3 . 2 m to x 1 = 3 . 7 m . Correct answer:- 52 . 565 J. Explanation: The potential energy is U ( x ) =- Z x (- Ax + B x 2 ) dx = Ax 2 2- B x 3 3 . If we take U (0) = 0, then the change in the potential energy is U = U ( x 1 )- U ( x ) = µ Ax 2 1 2- Bx 3 1 3 ¶- µ Ax 2 2- Bx 3 3 ¶ = • (11 N / m)(3 . 7 m) 2 2- (12 N / m 2 )(3 . 7 m) 3 3 ‚- • (11 N / m)(3 . 2 m) 2 2- (12 N / m 2 )(3 . 2 m) 3 3 ‚ =- 52 . 565 J . 004 (part 2 of 2) 10 points Find the change in kinetic energy of the par- ticle between the same two points. Correct answer: 52 . 565 J. Explanation: From conservation of energy (conservative force), the change of the kinetic energy is K =- U =- (- 52 . 565 J) = 52 . 565 J . keywords: 005 (part 1 of 2) 10 points A(n) 2300 g block is pushed by an external force against a spring (with a 25 N / cm spring constant) until the spring is compressed by 13 cm from its uncompressed length. The compressed spring and block rests at the bot- tom of an incline of 38 ◦ . Gozick, Brandon – Homework 10 – Due: Oct 13 2006, 5:00 pm – Inst: D Weathers 2 The acceleration of gravity is 9...
View Full Document

{[ snackBarMessage ]}

### Page1 / 6

Homework 10 - Gozick Brandon – Homework 10 – Due 5:00...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online