solutions_for_chapter_11

# solutions_for_chapter_11 - 19 Picture the Problem The fish...

This preview shows pages 1–2. 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: 19. Picture the Problem : The fish exerts a torque on the fishing reel and it rotates with constant angular acceleration. Strategy: Use Table 10-1 to determine the moment of inertia of the fishing reel assuming it is a uniform cylinder ( 2 1 2 MR ). Find the torque the fish exerts on the reel by using equation 11-1. Then apply Newton’s Second Law for rotation (equation 11-4) to find the angular acceleration and equations 10-2 and 10-10 to find the amount of line pulled from the reel. Solution: 1. (a) Use Table 10-1 to find I : ( 29 ( 29 2 2 1 1 2 2 0.99 kg 0.055 m 0.0015 kg m I MR = = = × 2. Apply equation 11-1 directly to find : τ ( 29 ( 29 0.055 m 2.2 N 0.121 N m r F τ = = = × 3. Solve equation 11-14 for : α 2 2 0.121 N m 81 rad/s 0.0015 kg m I τ α × = = = × 4. (b) Apply equations 10-2 and 10-10: ( 29 ( 29 ( 29 ( 29 2 2 2 1 1 2 2 0.055 m 81 rad/s 0.25 s 0.14 m s r r t θ α = = = = Insight: This must be a small fish because it is not pulling very hard; 2.2 N is about 0.49 lb or 7.9 ounces of force. Or maybe the fish is tired? 26. Picture the Problem : The person lies on a lightweight plank that rests on two scales as shown in the diagram at right. Strategy: Write Newton’s Second Law in the vertical direction and Newton’s Second Law for rotation to obtain two equations with two unknowns, m and cm x . Solve each to find m and cm x . Using the left side of the plank as the origin, there are two torques to consider: the positive torque due to the right hand scale and the negative torque due to the person’s mass. Solution: 1. (a) Write Newton’s Second Law in the vertical direction to find m : 2. (b) Write Newton’s Second Law for rotation and solve for x cm : Insight: The equation in step 1 does not depend on the axis of rotation that we choose, but the equation in step 2 does. Nevertheless, we find exactly the same cm x if we choose the other scale,...
View Full Document

{[ snackBarMessage ]}

### Page1 / 5

solutions_for_chapter_11 - 19 Picture the Problem The fish...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online