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Physics 111 Common Exam 1 February 15, 2002 Signature)______

Name (Print) ______4 Digit ID______Section ______

1.Suppose A = BC, where A has the dimensions l/m and C has the dimensions l/t. What are the dimensions of B?

A) t/m B) l2/tm C) tm/l2

D) l2t/m E) m/l2t

2.What is the value of the mixed dot and cross producti.(jXk)?

A) 0 B) +1 C) –1

D) 3 E) 31/2

3.Three vectors have the following magnitudes and directions from the positive x-axis:

a: 200m @ 45o , b: 400m @ 135o , and c: 200m @ 270o .

The vector sum of these three has an x – component of:

A) – 224 m B) – 141 mC) 0.00 m

D) + 141 mE) + 224 m

4.Starting at time t = 0, an object moves along a straight line. Its coordinate in meters is given by x(t) = 75t – 1.0t3, where t is in seconds. When it momentarily stops its acceleration is:

A) 0B) –73 m/s2C) –30 m/s2

D) –9.8 m/s2E) 9.2 x 103 m/s2

5.A particle moving at 4.0 m/s in the positive x direction only has an acceleration of 3.0 m/s2 in the positive y direction for 2.0 seconds. The final speed of the particle is:

A)-2.0 m/sB) 7.2 m/sC) 6.0 m/s

D) 10 m/sE) None of the above

6.A rifle is fired over level ground at an angle of 45 degrees above the horizontal. The muzzle velocity of the bullet is 490 m/s. How far does it travel horizontally before it hits the ground. Neglect air resistance.

A) 12,250 mB) 24,500 mC) 34,750 m

D) 49,000 mE) 98,000 m

7.A stone is tied to the end of a string and is swung with constant speed around a horizontal circle whose radius is 1.5 meters. If it makes two complete revolutions each second, its acceleration is:

A) 0.24 m/s2B) 2.4 m/s2C) 24 m/s2

D) 240 m/s2E) 2400 m/s2

8. An ant, crazed by the hot sun on a Texas afternoon, is crawling over an x-y plane scratched in the dirt. The x and y components (in cm.) of four consecutive moves a, b, c, and d are:

a = (30.0, 40.0), b = (bx, -70.0), c = (-20.0, cy), and d = (-80.0, -70.0).

The overall displacement after the four moves is -140.0 in the x direction and -20.0 for y.

What are a) the component bx, and b) the component cy?

What are c) the magnitude and d) the angle of the overall displacement?

Answers: a) bx = -70 cy = 80

c) 141 d) 1880

9.Cockroaches can run fast for short distances. Suppose that you turn on the light in a budget hotel and see a cockroach scurrying directly away from you in a straight line at a constant velocity of 1.50 m/s. You chase it with an initial velocity of 0.90 m/s. If you start 0.80 m behind the bug, what minimum constant acceleration would you need to catch up to it when it has traveled 1.20 m, just as it's about to safely duck behind a counter?

Ans. a = 4 m/s2

10. An unhappy member of a theater audience stands up and throws a rotten tomato at a ham actor on stage. The tomato travels a horizontal distance of 15.0 m in 0.75 seconds before hitting the actor's face with a splash, 1.7 m above the stage. The thrower relases the tomato 2.0 m above the horizontal floor of the theater, with an initial velocity v0 that is 190 above the horizontal. There is no air resistance.

a) Find the magnitude of the tomato's velocity when it is thrown. v0 = 21 m/s

b) How high is the stage above the floor of the theater?

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