PHY MIdterm 1

# PHY MIdterm 1 - Version A A wheel rotates from rest for 3.0...

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Version A 1. A wheel rotates from rest for 3.0 s with constant α = 4 0 . rad s . What angle in radians has it turned through? a. 15 b. 18 c. 12 d. 21 e. 24 ANS: b 2. A ball attached to a string moves clockwise in a vertical circular path in a uniform gravitational field directed downwards. What is the direction of the acceleration vector when the ball is at the position indicated in the diagram? ANS: a 3. A 660 N woman is sitting on a frictionless surface. She throws a 1.3 kg book at a speed of 15 m/s. What is her recoil speed in m/s? a. 0.29 b. 0.0027 c. 0.0028 d. 0.031 e. 0.33 ANS: a 4 . A uniform (full) sphere of radius R and mass M rotates (I cm =2/5mR 2 ) freely about a horizontal axis that is tangent to the sphere, as shown right. The moment of inertia of the sphere about this axis is: a. 2 5 2 MR . b. 2 3 2 MR . c. 2 7 5 MR . d. 2 5 7 MR . e. 2 2 3 MR . ANS:d 5 . A 3.0-kg mass is released from rest at point A of a circular frictionless track of radius 0.40 m as shown in the figure. The mass slides down the track and collides with a 1.4-kg mass that is initially at rest on a horizontal frictionless surface. If the masses stick together, what is their speed after the collision? a. 2.1 m/s b. 1.7 m/s c. 1.9 m/s d. 1.5 m/s e. 2.3 m/s ANS:c 6 A 1kg mass object moves from x = 0 m to x = 7 m subject to the force shown in the diagram. If the only work, is the work done by the force on the diagram. What is the object kinetic energy at x = 7m . At x=0 object was moving with the speed of 4m/s in the positive x direction. a. 68 b. 28 c. 20 d. -20 e. -40 ANS: a 7. A block is pushed across a rough horizontal surface from point A to point B by a force (magnitude P = 5 4 . N ) as shown in the figure. The magnitude of the force of friction acting on the block between A and B is 1.2 N and points A and B are 0.5 m apart. If the kinetic energies of the block at A and B are 4.0 J and 5.6 J, respectively, how much work in J is done on the block by the force P between A and B ? a. 2.7 b. 1.0 c. 2.2 d. 1.6 e. 3.2 ANS: c x (m) F x ( ) (N) 20 40 1 2 3 4 5 6 0 –20 –40 7 P A B a. b. c. d. e.

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Version B 1. A wheel rotates from rest for 3.0 s with constant α = 4 0 . rad s . What angle in radians has it turned through? a. 18 b. 15 c. 12 d. 21 e. 24 ANS: a 2. A ball attached to a string moves clockwise in a vertical circular path in a uniform gravitational field directed downwards. What is the direction of the acceleration vector when the ball is at the highest point of its path? ANS: d 3. A 660 N woman is sitting on a frictionless surface. She throws a 1.3 kg book at a speed of 15 m/s. What is her recoil speed in m/s? a. 0.033 b. 0.0027 c. 0.0028 d. 0.031 e. 0.29 ANS: e 4. A 3.0-kg mass is sliding on a horizontal frictionless surface with a speed of 3.0 m/s when it collides with a 1.0-kg mass initially at rest as shown in the figure. The masses stick together and slide up a frictionless circular track of radius 0.40 m. To what maximum height, h , above the horizontal surface will the masses slide? a.
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## This note was uploaded on 01/17/2010 for the course PHY PHY1321 taught by Professor Czajkowski during the Fall '08 term at University of Ottawa.

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PHY MIdterm 1 - Version A A wheel rotates from rest for 3.0...

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