Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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Ch#1

Section 1

Section 2

16- A car travels in a straight line at 40 km h-1 for 1 h and 60 km h-1 for 2 h.

(a) How far does it travel?

(b) Find the average velocity?

17- A woman wants to drive 100 km in 2 h. If she averages 40 km h-1 for the first 1.5 h, what average velocity must she maintain for the remaining time?

Section 4

38- A car initially moving at 20 m s-1 brakes with acceleration of 2 m s-2. How long will it take for the car to stop?

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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Section 5

43- A jet plane (����� ة�ط�) accelerates on a runway from rest at 4 m s-2. After 5 s, find its (a) distance traveled;

(b) Velocity.

Section 6

54- An antiaircraft shell (ات�د ط���� �����) is fired vertically upward with an initial velocity of 500 m s-1.

(a) Compute the maximum height of the shell.

(b) How long does it take to reach this height?

(c) When will the height be 1000 m?

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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62- A sandbag (ر�� ���) dropped from a balloon strikes the ground in 15 s. What was the height of the balloon if it was initially

(a) at rest in the air;

(b) descending (ر����) with a velocity of 20 m s-1

Problems

77- A girl rows 12 km downstream in 2 h. Her return trip takes 3 h.

(a) How fast can she row in still water?

(b) How fast is the current?

80- A sled starting from rest slides down a hill with uniform acceleration. It travels 12 m in the first 4 s. When will the sled have a velocity of 4 ms-1?

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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86- A sandbag is dropped from an ascending balloon that is 300 m above the ground and is ascending at 10 ms-1.

(a) What is the maximum height of the sandbag?

(b) Find the position and velocity of the sandbag after 5 s?

(c) How long does it take for the sandbag to reach the ground from the time it was dropped?

90- A rock is dropped into a well and a splash is heard 3 s later. If sound travels in air at 344 ms-1, how deep is the well?

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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Ch#2

Section 1

1- Figure 2.18 shows a collection of vectors that can be combined in various ways. For example, A+C=B. Find (a) E+C; (b) A+F; (c) A+D; (d) E+A; (e) E+2A; (f) A-B; (g) B-A; (h) C-A.

Fig. 2-18

2- In Fig. 2.19, for what value of θ will C=A+B have (a) a maximum magnitude, and

(b) a minimum magnitude? (c) Find C when θ = 90°.

Fig. 2-19

A=5

B=12

θ

B D

E

H

G

F

C

A

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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3- A vector has an x component of -10 and a y component of +3. (a) Draw a set of x-y axes and show the vector. (b) Calculate the magnitude and direction of the vector.

4- �� � 3�̂ � 2̂, �� ��� � 4�̂ � ̂. Find the magnitude of (a) A+B; (b) A-B; (c) 2B.

5- �� � 2�̂ � 4̂,Find the magnitude and direction of (a) A; (b) –A.

6- If θ=72° in fig. 2.19, find (a) the direction and magnitude of C=A+B by constructing a drawing using a ruler and protractor; (b) the direction and magnitude of C using the component method.

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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7- For the vectors A and B in Fig. 2.20, find (a) A+B; (b) B-A; (c) A-B.

Fig. 2.20

8- Using components for the vectors in Fig. 2.21, find the direction and magnitude of E=A+B+C+D.

Fig. 2.21

9- Using components for the vectors in Fig. 2.21, find the direction and magnitude of F=A+B-C+2D.

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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10- A woman walks 10 km north, turns toward the northwest, and walks 5 km further. What is her final position?

11- A ship sets out to sail 100 km north but is blown by a severe storm to a point 200 km east of its starting point. How far must it sail, and in what direction, to reach its intended destination?

12- One person walks northeast at 3 km h-1, and another heads south at 4 km h-1. How far apart are they after 2 h?

13- For the vectors in Fig. 2.22, find the magnitude and direction of (a) D=A+B+C; (b) E=A-B-C.

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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14- For the vectors in Fig. 2.22, find the magnitude and direction of (a) D=A+B+C; (b) E=A-B-C.

Ch#3 Section 1 Section 2 Section 3 Section 5 Section 6 Section 8 47- An elevator of mass 900 kg accelerates upward at 3 ms-2. What is the tension in the cable where it is attached to the elevator? 50- A 60-kg man hangs from a light cable suspended from a helicopter. Find the tension in the cable if the acceleration is (a) 5 ms-2 upward; (b) 5 ms-2 downward.

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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51- A human femur will fracture if the compressional force is 2×105 N. A person of mass 60 kg lands on one leg, so that there is a compressional force on the femur. (a) What acceleration will produce fracture? (b) How many times the acceleration of gravity is this?

55- A tennis ball of mass 0.058 kg initially at rest is served at a velocity of 45 ms-1. If the racket is in contact with the ball for 0.004 s, what is the net force on the ball during the serve? (Assume the acceleration is constant.) Section 12

Problems 87- A woman of mass 55 kg steps off a rock, striking the ground at 5 ms-1. (a) If she lands on her feet with her body held rigid, she stops in 0.15 m. What average force is exerted upward on the woman during the impact? (b) If she flexes her legs and body during the impact, she stops in 0.5 m. What average force does she now experience during impact?

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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90- In Fig. 3-26, the string and the pulley are massless, and there is no friction. If m1=m2=5 kg, find (a) the tension in the string; (b) the acceleration.

Fig. 3-26 100- In Fig. 3-27, the string and the pulley are massless, and there is no friction. Find (a) the tensions in the strings; (b) the acceleration of the system.

Fig. 3-27

Al-Farabi College Physics, Kane Dr. Said Moh’d Azar

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102- In Fig. 3-28, the string and the pulley are massless, and there is no friction. Find (a) the tensions in the strings; (b) the acceleration of the system.

Fig. 3-28