COLLEGE OF FOUNDATION AND GENERAL STUDIES PUTRAJAYA CAMPUS FINAL EXAMINATION TRIMESTER I 2012/2013 PROGRAMME SUBJECT CODE SUBJECT : Foundation in Engineering : PHYF115 : Physics I DATE : September 2012 TIME VENUE : 2 ½ hours : Library Exam Hall INSTRUCTIONS TO CANDIDATES: 1. This paper consists of TEN (10) questions in Part A and FIVE (5) questions in Part B in FIVE (5) pages. 2. Answer ALL questions in Part A and ANY FOUR(4) questions in Part B. 3. Write ALL answers in the answer booklet provided. 4. Write answer to each question in Part B on a new page. THIS QUESTION PAPER CONSISTS OF 6 PRINTED PAGES INCLUDING THIS COVER PAGE. Page 1 of 6
Part A: (Answer ALL questions - each question is worth 2 marks) Constants: g = 9.80 ms -2, G = 6.67 x 10-11 N.m 2 kg -2 1. An ore loader moves 1.6 x 10 3 tons/h from a mine to the surface. Convert this rate to lb /s. (1 ton = 2 x 10 3 lb) 2. A particle moves according to the equation x =10t 2, where x is in meters and t is in second. Find the average velocity from 2.00 s to 2.50 s. 3. One point in a plane has polar coordinates (2.50 m, 30.0 o ). Determine the Cartesian coordinate of this point. 4. A 2.00-kg crate is placed on a friction inclined plane of angle θ = 30 o as shown in Figure 1. Draw all forces acting on the box in x- and y- axis. Determine the acceleration, a of the crate after it is released if the friction coefficient is zero. y x Figure 1 5. A 500-g object is swung in a vertical circular path on a string 1.00 m long. If its speed is 4.00 ms -1 at the top of the circle, what is the tension in the string there? 6. A 700-kg elevator starts from rest. It moves upward for 3.00 s with constant acceleration until it reaches its cruising speed of 2.00 ms -1. What is the average power of the elevator motor during this period? Page 2 of 6
7. A 4.0-kg ball with an initial velocity of (5 + 3 ) m/s collides with a wall and rebounds with a velocity of ( 4 + 3 ) m/s. What is the impulse exerted on the ball by the wall? 8. The turntable of a record player has an angular velocity of 8.00 rads -1 when it is turned off. The turntable comes to rest 2.50 s after being turned off. Through how many radians does the turntable rotate after being turned off? Assume constant angular acceleration. 9. A particle whose mass is 3.00 kg moves in the xy plane with a constant speed of 3.50 ms -1 along the direction relative to the origin?. What is its angular momentum 10. Figure 2 shows a 5.00-kg beam 2.00 m long that is used to support a 10.00 kg sign by means of a cable attached to a building. What is the tension exerted by the beam on the cable? 40º JOE S JOE S DINNER Figure 2 Page 3 of 6
Part B: (Answer ONLY 4 questions - each question is worth 10 marks) QUESTION 1 a) A particle undergoes the following consecutive displacements: 3.50 m south, 8.20 m northeast, and 15 m west. What is the resultant displacement? [4] b) A golf ball is hit off a tee at the edge of a cliff. Its x and y coordinates as functions of time are given by the following expressions: x = (14.0 ms -1 )t and y = (8.00 ms -1 )t (4.90 ms -2 )t 2 i. Write a vector expression for the ball s position as a function of time, using the?i? j unit vectors and. [1] ii. By taking derivatives, obtain expressions of the velocity vector v as a function of time [2] iii. Use unit-vector notation to write expressions for the velocity, v and the acceleration, a of the golf ball, at t = 3.00 s. [3] QUESTION 2 Figure 3 shows a 5.00-kg object that is attached to a vertical rod by two strings. The object rotates in a horizontal circle at constant speed of 6.00 ms -1. Find the tension in a) the upper string and [5] b) the lower string. [5] Figure 3 Page 4 of 6
QUESTION 3 a) A 2.50-kg block is projected down a plane that makes an angle θ = 15 o with the horizontal with an initial velocity of 1.90 ms -1. If the coefficient of kinetic friction between the block and plane is 0.40, determine i) the initial kinetic energy; [1.5] ii) the friction force; and [1.5] iii) the distance of the block slide down the plane before coming to rest? [3] b) Two automobiles approach an intersection. One vehicle with a mass of 1200 kg is traveling with velocity 13.0 ms -1 toward the east. The other vehicle with a mass of 2000 kg is traveling north with velocity, v 2i. The vehicles collide in the intersection and stick together, and move at an angle of 55.0 o north of east, with final velocity, v f. Find i) final velocity, v f ; and [2] ii) initial velocity, v 2i. [2] QUESTION 4 a) A wheel of radius 0.300 m is mounted on a frictionless, horizontal axis. The moment of inertia of the wheel about the axis is 0.050 kgm 2. A light cord wrapped around the wheel supports a 0.800-kg object as shown in the Figure 4. The object is released from rest. What is the magnitude of the acceleration of the 0.800-kg object? Find i) the tension of the cord; and [5] ii) the acceleration of the object. [1] Page 5 of 6 Figure 4
b) A particle of mass m = 0.200 kg and speed v 0 = 7.00 ms -1 collides and sticks to the end of a uniform solid cylinder of mass M = 4.00 kg and radius R = 30.0 cm as shown in Figure 5. If the cylinder is initially at rest and is pivoted about a frictionless axle through its center, what is the final angular velocity of the system after the collision? [4] Figure 5 QUESTION 5 (a) State Kepler s Third law [2] (b) A small satellite of earth has an orbital period of 0.750 days and orbital radius of 2.15 x 10 7 m. Find (i) the mass of the earth; [4] (ii) the gravitational field of earth at the satellite; and [2] (iii) the linear speed of satellite. [2] - END OF QUESTION PAPER- Page 6 of 6