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Kingsborough Community College, CUNY Department of Physical Sciences PHY 1100 Midterm 2 Review Prof

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Kingsborough Community College, CUNY Department of Physical Sciences PHY 1100 Midterm 2 Review Prof. Richard Garavuso Instructions: You must show all work. Correct answers without sufficient justification will receive no credit. In your solutions, derive symbolic expressions prior to plugging in data. When you do plug in data, be sure to include appropriate units. Furthermore, be sure to clearly express your final answer to each question with appropriate units. You may use the following table. 1) A 1000 kg car is moving at 30 m/s around a horizontal unbanked curve whose diameter is 0.20 km. What is the magnitude of the friction force required to keep the car from sliding? 2) By how many newtons does the weight of a 100 kg person decrease when he goes from sea level to mountain top at an altitude of 5000 m? The mean radius of the earth is 6.38 × 106 m. 3) If the earth were twice as far from the sun as it presently is, how long (in terms of the present year) would it take it to make one orbit around the sun? 4) A stone is moving on a rough level surface. It has 24 J of kinetic energy, and the friction force on it is a constant 0.50 N. What is the maximum distance it can slide? 5) A block slides down a frictionless inclined ramp and experiences no significant air resistance. If the ramp angle is 17.0° above the horizontal and the length of the surface of the ramp is 20.0 m, find the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at the top. 6) On a planet where g = 10.0 m/s2 and air resistance is negligible, a sled is at rest on a rough inclined hill rising at 30° as shown in the figure. The object is allowed to move and it stops on a rough horizontal surface, at a distance of 4.0 m from the bottom of the hill. The coefficient of kinetic friction on the hill is 0.40. What is the coefficient of kinetic friction between the horizontal surface and the sled? 7) A golf club exerts an average horizontal force of 1000 N on a 0.045 kg golf ball that is initially at rest on the tee. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball just as it leaves the tee? 8) A 550 g ball traveling at 8.0 m/s undergoes a sudden head-on elastic collision with a 250 g ball traveling toward it also at 8.0 m/s. What is the speed of the 250 g mass just after the collision? 9) A 1200 kg car moving at 15.6 m/s suddenly collides with a stationary car of mass 1500 kg. If the two vehicles lock together, what is their combined velocity immediately after the collision? 10) A torque of 12 N · m is applied to a solid, uniform disk of radius 0.50 m. If the disk accelerates at 1.6 rad/s2, what is the mass of the disk? 11) A solid uniform ball with a mass of 125 g is rolling without slipping along the horizontal surface of a table with a speed of 4.5 m/s when it rolls off the edge and falls towards the floor, 1.1 m below. What is the rotational kinetic energy of the ball just before it hits the floor? 12) A figure skater rotating at 5.00 rad/s with arms extended has a moment of inertia of 2.25 kg · m2. If he pulls in his arms so his moment of inertia decreases to 1.80 kg · m2, what will be his new angular speed? Location of axis Moment of inertia Object Axis (a) Thin hoop, radius R Through center R MRP Axis (b) Thin hoop, radius R width w Through central diameter R MR2 + 1MW2 Axis (c) Solid cylinder, radius R Through center R 2MR2 (d) Hollow cylinder, inner radius R outer radius R2 Through center JAxis TR] 3M(R+ R3) R2 Axis (e) Uniform sphere, radius R Through center R MR2 Axis (f) Long uniform rod, length Through center 12 M2 Axis Long uniform rod, length Through end Me Axis (h) Rectangular thin plate, length l, width w Through center M(2 + w2) 2014 Pearson Education, Inc. Moments of inertia for various objects of uniform composition, each with mass M.