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Unformatted text preview: practice 06 ALIBHAI, ZAHID 1 Latest unpenalized work: Feb 25 2007 Sunday 04:00 (after this date you can not make a perfect score). Work cutoff: Feb 25 2007, 4:00 am. Question 1 part 1 of 3 10 points A block starts at rest and slides down a frictionless track except for a small rough area on a horizontal section of the track (as shown in the figure below). It leaves the track horizontally, flies through the air, and subsequently strikes the ground. The acceleration of gravity is 9 . 81 m / s 2 . =0 . 3 1 . 2 m b b b b b b b b b b b b 500 g h 1 . 9m 3 . 42 m 9 . 81m / s 2 v At what height h above the ground is the block released? Answer in units of m. Question 2 part 2 of 3 10 points What is the the speed of the block when it leaves the track? Answer in units of m / s. Question 3 part 3 of 3 10 points What is the total speed of the block when it hits the ground? Answer in units of m / s. Question 4 part 1 of 3 10 points A block of mass m is pushed a distance D up an inclined plane by a horizontal force F . The plane is inclined at an angle with respect to the horizontal. The block starts from rest and the coefficient of kinetic friction is k . m D k F If N is the normal force, what is the work done by friction? 1. W =- k N D 2. W =- k ( N - mg cos ) D 3. W = + k ( N + mg cos ) D 4. W =- k ( N + mg cos ) D 5. W = + k ( N - mg cos ) D 6. W = 0 7. W = + k N D Question 5 part 2 of 3 10 points What is the work done by the normal force N ? 1. W = N D sin 2. W = N D 3. W = ( N + mg cos + F sin ) D 4. W =-N D 5. W = ( mg cos + F sin - N ) D 6. W = N D cos 7. W = ( N - mg cos - F sin ) D 8. W = 0 Question 6 part 3 of 3 10 points practice 06 ALIBHAI, ZAHID 2 What is the final speed of the block? 1. v = radicalbigg 2 m ( F cos - mg sin + k N ) D 2. v = radicalbigg 2 m ( F cos - mg sin - k N ) D 3. v = radicalbigg 2 m ( F sin + k N ) D 4. v = radicalbigg 2 m ( F cos + mg sin ) D 5. v = radicalbigg 2 m ( F sin - k N ) D 6. v = radicalbigg 2 m ( F cos + mg sin - k N ) D 7. v = radicalbigg 2 m ( F cos - k N ) D 8. v = radicalbigg 2 m ( F cos - mg sin ) D Question 7 part 1 of 1 10 points A 0 . 3 kg mass is initially at rest and is free to move with negligible friction along the x- axis. The figure below shows the value of an applied force as a function of time.- 1 1 2 3 4 5 1 2 3 4 5 6 7 8 9 10 b b b b b b b b b b b b b b b b b b b b b b time ( s ) t Force(N) Calculate the kinetic energy K of the mass when it reaches 5 s. Answer in units of J....
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