Physics Exam Questions2

Physics Exam questions (2)

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1. Suppose a man’s scalp hair grows at a rate of 0.34 mm per day. What is this growth rate in centimeters per year (cm/y) ?

2. A train is travelling on straight tracks. The velocity of a train is 25.0 m/s , due east. Three minutes later its velocity is 16.0 m/s , due east. What is the train’s average acceleration? (Determine both the magnitude and direction of the average acceleration.)

3. From ground level a ball is thrown vertically upward, which is the positive direction. Two seconds later it reaches the top of its flight path where it comes to a momentary halt. What is the maximum height of the ball in the air above the ground? (Neglect air resistance.)

4. A toy cannon shoots a pellet with an initial speed of v0=10 m/s at a fixed angle above the horizontal floor. The horizontal component of the initial velocity of the pellet is v0x= 5 m/s. Determine angle at which the pellet was shot with respect to the floor.

5. A 18.0-kg sled is being pulled across a horizontal snowy road at a constant velocity. The pulling force is parallel to the horizontal road and the coefficient of kinetic friction between the sled and snow is 0.15 . Determine the magnitude of the pulling force.

6. A model airplane on a guideline moves at a constant speed on a circle that is parallel to the ground. The model airplane has a mass of 0.90 kg . The path of the airplane and its guideline lie in the same horizontal plane, because the weight of the plane is balanced by the lift generated by its wings. Find the magnitude of the tension force T in the guideline (length= 18 m) for speed of 20 m/s .

7. It takes 300 kJ of work to accelerate a car from 14.0 m/s to 26.0 m/s . What is the car’s mass?

8. An 88.0-kg skydiver with an open parachute falls straight downward through a vertical height of 400 m. The skydiver’s velocity remains constant. What is the work done by the nonconservative force of air resistance, which is the only nonconservative force acting?

9. A roller coaster moves with a speed of 17.5 m/s at the bottom of the valley on its track. Then the roller coaster starts up a 15 m-hill. What speed will it attain when it reaches the top? Assume that friction and air resistance are absent.

10. An audio compact disk (CD) has a playing time of 74 minutes. When the music starts, the CD is rotating at an angular speed of 480 revolutions per minute (rpm) and during the playback the rotation slows down. The average angular acceleration of the CD is α = -3.65 rev/min2. Find the angular speed at which the CD is rotating at the end of the music. Express your answer both in rev/min and also in rad/s.

11. A hiker, who weighs 780 N, is walking through the woods and crosses a small horizontal bridge. The bridge rests on two concrete supports, one at each end. He stops one-fourth of the way along the bridge. Assume that the board of the bridge has negligible weight. What is the magnitude of the force that a concrete support exerts on the bridge (a) at the far end and (b) at the near end ?