Applied Physics Department Semester: Fall 2009 College of Sciences Date: October 14, 2009 University of Sharjah Time: 4:00 4:50 pm

Physics (1) (1430115)

Examination 1

Instructor: DR. Hussain Dr. Ala

Student Name : Student ID number : .

Section number :

MCQ Question 1 Question 2 Question 3 Total

MarkAssigned 5 5

5 5 20

Mark Obtained

Please read the following instructions carefully: The exam is made up of 5 pages, including the cover page

The test is made up of 2 parts. Part I Multiple Choice Question (MCQ), please make sure you indicate your choice. If choices are not clearly indicated, the first ones will be counted. Part II Essay Problems : Solve in full. Write the answers clearly and box

or encircle the final results. Notes and books are not allowed. However, formulas and information you might need are given in a separate sheet of paper

Calculators are permitted Dictionaries of any type are not allowed. If you have questions, ask only the instructor of your course

1

Part I - Multiple Choice Question (5 points)

Choose the one alternative that best answers the question 1) An object moving along a straight line is decelerating. Which one of the following

statements concerning the objects acceleration is necessarily true?(a) The value of the acceleration is positive.

(b) The direction of the acceleration is in the same direction as the displacement.

(c) The direction of the acceleration is in the direction opposite to that of the velocity.

(d) An object that is decelerating has a negative acceleration.

2) Which one of the following situations is not possible?(a) A body travels with a constant acceleration and a time-varying velocity.

(b) A body travels with a northward velocity and a northward acceleration.

(c) A body travels with a northward velocity and a southward acceleration.

(d) A body travels with a constant velocity and a time-varying acceleration.

3) A ball is hit upward and travels along a parabolic arc before it strikes the ground. Which one of the following statements is necessarily true?

(a) The x-component of the ball velocity is the same during the balls flight.

(b) The acceleration of the ball decreases as the ball moves upward.

(c) The velocity of the ball is zero when the ball is at the highest point in the arc.

(d) The acceleration of the ball is zero when the ball is at the highest point in the arc.

4) At a given instant, the acceleration of a certain particle is zero. This means that (a) The velocity is constant.

(b) The velocity is increasing.

(c) The velocity is decreasing.

(d) The velocity is not changing at that instant.

5) A baseball player throws a ball horizontally. Which statement best describes the balls motion after it is thrown? [Neglect the effect of air resistance].

(a) Its vertical speed remains the same, and its horizontal speed increases.(b) Its vertical speed increases, and its horizontal speed increases.

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(c) Its vertical speed remains the same, and its horizontal speed remains the same.(d) Its vertical speed increases, and its horizontal speed remains the same.

Part II Essay Questions Question 1 (5 points) A toy car moves 80.0m horizontally, then 110.0 m at an angle of 30.0o above the horizontal. It then travels 150.0 m at an angle of 50.0o below the horizontal, as shown below. The time taken for the whole trip is 3.0 minutes .

(a) Determine the magnitude and direction of the total displacement?(b) What is the car average velocity for the entire trip? (c) What is the car average speed for the entire trip.

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x

y

150m

30o

110m

End

50o

80mStart

Question 2 (5 points)A bullet is fired horizontally from a gun that is 45.0 m above flat ground, with an initial velocity of 250 m/s.

(a) How much time does the bullet remain in the air before hitting the ground? (b) At what horizontal distance from the firing point does it strike the ground? (c) What is the speed of the bullet just before it hits the ground? (d) What is the acceleration of the bullet just before it strikes the ground.

4

5

Question 3 (5 points)On takeoff, the combined action of the engines and wings of an airplane exerts an 8000N force on the plane, directed upward at an angle of 65.0 above the horizontal. The plane rises with constant velocity in the vertical direction while continuing to accelerate in the horizontal direction. Ignore the air resistance.

(a) What is the weight of the plane?(b) What is its horizontal acceleration?(c) What is the net force (magnitude and direction) on the plane?

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65

8000 N

Applied Physics Department Semester: Fall 2009 College of Sciences Date: October 14, 2009 Physics (1) Examination 1 Instructor: DR. Hussain Dr. AlaQuestion 2Question 3Total Mark

Please read the following instructions carefully: