King Saud University College of Science Department of Physics and Astronomy Girls section Second Term 1435-36 Tuesday, May 19, 2015 PHYS-145 Make-up to First Midterm 10:00 - 11:30 p.m. Name: ID number: Section: Classroom: Write your selected answer for each question here: Q1 Q2 Q3 Q4 Q5 B A C E D Q6 Q7 Q8 Q9 Q10 A D B D C Q11 Q12 Q13 Q14 Q15 E B E A C 1) Please do not forget to write your name and I.D. number on this page 2) Separate this page from the other pages and return ONLY this page at the end of the exam. Assume g = 9.8 m/s2 in all questions. PHYS 145_MIDTERM I_MAKE-UP_SPRING 2015 1. If vector A is parallel and equal in magnitude to vector B , the magnitude of 3A+2B is : A) 4A B) 5B 2. The angle between vector A) 0o B) 45o C) 0 ̂ D) 2A ̂ and vector C) 90o E) 3B ̂ ̂ is: D) 120o E) 180o 3. Which of the following sentences is FALSE? A) Action and reaction forces act on different objects. B) Action and reaction forces have opposite directions C) Action and reaction forces act on the same object. D) Action and reaction forces have the same magnitude. E) Action and reaction forces can be either contact forces or field forces. 4. Suppose that an object is accelerating at a rate of 10 m/s2. If the magnitude of the net force is doubled and the mass is quadrupled, what is the new acceleration of this object? A) 3.5 m/s2 B) 9.5 m/s2 C) 4 m/s2 D) 12 m/s2 E) 5 m/s2 5. If the kinetic friction coefficient is 0.15, then the acceleration of a 15 kg box down a 30° slope will be: A) − 0.36 m/s2 B) Zero C) −3.63 m/s2 D) 3.63 m/s2 E) 0.39 m/s2 6. A ball is thrown with a force of 30 N. The ball has an acceleration of 3 m/s2. The mass of the ball is: A) 10 kg B) 10 N C) 90 kg D) 3.06 N E) 9.2 kg 7. A box of a mass 10 kg slides from rest on an inclined plane as in the Figure. Neglecting the frictional force, the magnitude of its acceleration is: A) 14.9 m/s2 B) 49 m/s2 C) 9.8 m/s2 PHYS 145_MIDTERM I_MAKE-UP_SPRING 2015 D) 4.9 m/s2 E) 2.5 m/s2 30° 8. A body is moving along a straight line at 40 m/s undergoes an acceleration of 4 m/s2. After 20 seconds its speed will be: A) 20 m/s B) 120 m/s C) 160 m/s D) 80 m/s E) 40 m/s 9. The distance (x) in meters travelled by an object is related to time (t) in seconds by the equation of motion: x = 10t + 4t2. The acceleration of the object is: A) 40 m/s2 B) 14 m/s2 C) 4 m/s2 D) 8 m/s2 E) 2.5 m/s2 10. A car starts from rest and covers a distance of 50 m in one second with uniform acceleration. Its acceleration is: A) 200 m/s2 B) 50 m/s2 C) 100 m/s2 E) 150 m/s2 D) zero 11. An object weighting 40 N is released from a height of 10 m. Just before it touches the ground, its kinetic energy is: A) 3920 J B) 250 J C) 2500 N D) 4 N/m E) 400 J 12. If the velocity of an object is doubled then its kinetic energy is: A) Doubled B) Quadrupled C) Halved D) Tripled E) No Change 13. A man carries a load of 500 N to a distance of 100 m. The work done by him on the load is: A) 5 N C) 5×104 J B) 50 N D) 1/5 J E) zero 14. A boy of 50 Kg runs up the stairs of length 25 m, inclined at an angle of 30° to the horizontal in 1 minute at constant speed. His average Power is at least A) 102 W B) 86 W C) 75 W D) 300 W E) 108 W 15. A body reaches the bottom of a slope with a speed of 10 ms-1. Due to friction with the ground it comes to a stop. If the coefficient of kinetic friction is 2, how far will he skid before coming to halt? A) 8.5 m B) 10.7 m PHYS 145_MIDTERM I_MAKE-UP_SPRING 2015 C) 2.6 m D) 100.3 m E) 4.7 m

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