Question

positive direction) Multiple Choice 15% each! 1. A solid uniform sphere of mass 1.85 kg and diameter 45.0 cm spins about an axle through its center. Starting with an angular velocity of 2.40 revisit stops after turning through 18.2 rev with uniform acceleration. The net torque acting on this sphere as it is slowing down is dosest to (A) 0.0466 Nm (B) 0.00593 Nm (C) 0.0620 Nm (D) 0.149 Nm (E) 0.0372 Nm 2. If the torque on an object adds up to zero (A) The forces on it also add up to zero. (B) The object is at rest. The object could be both turning and accelerating linearly. (D) The object could be accelerating linearly but it could not be turning (E) The object cannot be turning, 3. A spinning ice skater is able to control the rate at which she rotates by pulling in her arms. We can best understand this effect by observing that in this process (A) her moment of inertia remains constant. (B) she is subject to a constant nonzero torque. (C) her total velocity remains constant. (D) her angular momentum remains constant (E) her kinetic energy remains constant A solid disk and a solid sphere are released simultaneously at the top of an inclined plane. They roll down without slipping Which will reach the bottom first? (A) the sphere (B) the one of smallest diameter (C) the one of greatest mass (D) the disk (E) at the same time. 5. A uniform piece of wire, 20 cm long is bent in a right angle in the center to give it an L-shape. How far from the bend is the center of mass of the bent wire? (A) 25 cm (B) 3.5 cm (C) 5.0cm (D) 7.1 cm (E) 4.5 cm 6. In rotational dynamics, moment of inertia plays a role analogous to one of the quantities encountered in linear motion, namely (A) translational kinetic energy (B) impulse (C) mass (D) momentum (E) a "couple" or "moment of a force 7. A uniform solid sphere has a moment of inertial about an axis tangent to its surface. The moment of inertia of this sphere about an axis through its center is (A) 7/51 (B) 3/51 (C) 2/71 (D) 2/5 (E) 1171 5. A 550 g mass traveling at 8.0 m/s undergoes a head-on elastic collision with a 250 g mass traveling toward it also at 8.0 ms. What is the speed of the 250 g mass after the collision? (A) 14 m/s (B) 8.0 m/s (C) 15m/s (D) Om/s (6) 4.0m/s

Answer 1

m 1.86 H O.45m 45 cm C o. 225m N2.4ev/S N O Aange aydar velualy us 2T (2.4+0 2.4 T ad ls 2 Ayular diphcement () G= 2T X1. 2 Gadian. 3 6.4 T Srad Time eguicned () = e 2.4 TT t - 15.17S A cceleraton l) Agelar d2T (N2- N.) = 2T (0-2.4) 15.17 d 0.9949Ad/ s Net Toogve achy ansphere l whene, I- 2 mgi 2 x 85X 0.225%X 0.994 N -m O.0372 N-m Cosrect uwen Hence, op hon e)0.0372 N-m