{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

exam 2 fall 2009

# exam 2 fall 2009 - wweeeThis and the next question refer to...

This preview shows pages 1–4. Sign up to view the full content.

wweeeThis and the next question refer to the following situation: A puck of mass 1 kg collides with a wall. The puck will explode if hit with a force greater than 15 N. Before the collision the puck's velocity is 10 m/s. After the collision the puck's velocity is - 10 m/s. Assume a constant force is applied to the puck during the collision. What is the shortest time interval over which this puck could have been hit such that it did not explode? (a) 2.33 s (b) 1.33 s (c) 0.33 s (d) 0.033 s (e) 0.0033 s QUESTION 2* The mass of the puck is doubled. The initial and final velocity are the same as given above. The puck will explode if hit with a force greater than 15 N, as above. The time interval over which the puck is hit is the same as given for the answer in the previous question. Which one of the following statements is accurate? (a) The puck doesn't explode. (b) The puck explodes. (c) Not enough information is given to determine if the puck explodes. QUESTION 3** This and the next question refer to the following situation: A 0.001 kg bullet is fired from a gun and lodges inside a wooden block of mass 0.2 kg. The block and bullet then slide on a rough floor with a coefficient of kinetic friction μ k = 0.4 before coming to rest after sliding a distance of 3 m. Compare KE i , the initial kinetic energy of the bullet, with W f , the macroscopic work done by the frictional force between the block and the floor in stopping the block.

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

View Full Document
(a) KE i < W f (b) KE i = W f (c) KE i > W f QUESTION 4* The initial velocity of the bullet was: (a) 440 m/s (b) 680 m/s (c) 975 m/s (d) 1175 m/s (e) 1600 m/s QUESTION 5* This and the next two questions refer to the following situation: A 5 kg block slides on a horizontal, frictionless surface with a velocity of 2 m/s. It collides with an ideal, massless spring which is attached to a 15 kg block which is initially at rest. The spring has a spring constant of k = 50 N/m. At the instant the spring is maximally compressed, both masses will be traveling with a common velocity of: (a) 0.25 m/s (b) 0.5 m/s (c) 1 m/s (d) 1.5 m/s (e) 2 m/s QUESTION 6** When the spring is maximally compressed, how do the magnitudes of the acceleration of the two blocks compare?
(a) The acceleration of the 5 kg block is 3 times the acceleration of the 15 kg block.

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.

{[ snackBarMessage ]}