Physics 201 MWF 10:20 Fall 2000 (Ford)

Exam II Chapts. 5-7 in Cutnell and Johnson 4th ed.

Show all your work. Partial credit will be given if earned. Write your answers in the blanks provided.


(18 pts) 1. A motorcycle stunt driver drives his cycle around the inside of a vertical circular tracd. The motorcycle and rider have a combined mass of 150 kg. The motorcycle travels at a constant speed of 18 m/s in a circle of radius 20 m. What is the magnitude of the normal force exerted on the motorcycle by the track at each of the points A, B, and C shown in the sketch?

Ans. point A ________________

point B _______________

point C ______________




(22 pts) 2. A small rock of mass m = 0.50 kg is attached to a vertical rod by a light string. The system is rotated and the rock travels in a horizontal circle of radius 0.15 m. As the rock rotates the tension in the string is observed to be 5.5 N.

a) What is the angle that the string makes with the vertical?

Ans. _________________

b) What is the speed of the rock?

Ans. _______________


(20 pts) 3. A 60-kg skier coasts up a snow-covered slop that makes an angle of 37° with the horizontal. The initial speed of the skier at point A in the sketch is 12 m/s. After coasting a distance of 8.0 m up the slope to point B, the speed of the skier is 6.0 m/s. How much work has been done on the skier by the kinetic friction force that acts on the skier as she moves from point A to point B?

Ans. ________________


(20 pts) 4. Two cars, one traveling east and the other traveling north, arrive at an intersection and collide. The cars become stuck together as a result of the collision. Immediately after the collision the combined object (mass 2000 kg) has a velocity with magnitude 8 m/s at an angle of 37° north of east, as shown in the sketch. Car A has mass 800 kg and car B has mass 1200 kg. The road surface at the intersection is icy so friction between the cars and the road can be neglected. What are the speeds of cars A and B before the collision?

Ans. car A ______________

car B _____________


(20 pts) 5. A bullet of mass 0.015 kg moving to the right with a horizontal velocity of 300 m/s strikes a 2.0-kg wood block that is initially moving to the left toward the bullet with a speed of 4.0 m/s. The bullet passes through the block and is traveling to the right with a horizontal velocity of 100 m/s after it exits the block. All velocities are relative to the earth. What is the speed of the block after the bullet has passed through it, and is the block traveling to the left or to the right after the bullet exits?

Ans. speed ___________

left or right? ___________