1995 Physics Olympiad Screening Test (Part 1) Printer Friendly Version
1. The accompanying figure is a graph of an object’s position as a function of time.

Which lettered segment corresponds to a time when the object has a negative acceleration?
2. A car is moving at a constant velocity to the right along a straight level highway. Just as the car passes a cliff, a rock falls straight down in the cliff’s reference system. Which of the accompanying curves best depicts the path the rock takes in the car’s reference system?
3. Three blocks – 1, 2, and 3 – rest on a horizontal frictionless surface, as shown in the accompanying figure. Each block has a mass m, and the blocks are connected by massless strings. Block 3 is pulled to the right by a force F.

The resultant force on block 2 is:
4. Which solid vector in the accompanying figures best represents the acceleration of a pendulum mass at an intermediate point in its swing?
5. A mass attached to a horizontal massless spring is displaced 16 cm to the right of its equilibrium position and released from rest. At its 16 cm extension, the spring-mass system has 1.28 joules of potential energy.

Upon release, it slides across a rough surface and comes momentarily to rest 8 cm to the left of its equilibrium position. How much mechanical energy was dissipated by friction?
6. Two identical masses m are connected to a massless string which is hung over two frictionless pulleys as shown.

If everything is at rest, what is the tension in the cord?

7. Car A and car B are both traveling down a straight highway at 25 m/s (about 56 mph). Car A is only 6.0 m behind car B. The driver of car B brakes, slowing down with a constant acceleration of 2.0 m/s2 . After a time 1.2 s, the driver of car A begins to brake, also at 2.0 m/s2. What is the relative velocity of the two cars when they collide? Hint: Both cars are still moving forward when they collide.
8. During the collision between car A and car B described in Problem #7 above, which car experiences the greater change in momentum?

9. A 70-kg hunter ropes a 350-kg polar bear. Both are initially at rest, 30 m apart on a frictionless and level ice surface. When the hunter pulls the polar bear to him, the polar bear will move:
10. A bullet of mass m is fired at a block of mass M initially at rest. The bullet, moving at an initial speed v, embeds itself in the block. The speed of the block after the collision is:
11. The driver of a 1000-kg car tries to turn through a circle of radius 100 m on an unbanked curve at a speed of 10 m/s. The maximum frictional force between the tires and the slippery road is 900 N. The car will:

12. A solid cylinder weighing 200 N has a fixed axis and a string wrapped around it. The string is pulled with a force equal to the weight of the cylinder. The acceleration of the string is approximately:
13. A spinning ice skater has an initial kinetic energy (½)Iω2. She pulls in her outstretched arms, decreasing her moment of inertia to (¼)I. Her new angular speed is:
14. A heavy rod of length L and weight W is suspended horizontally by two vertical ropes as shown below. The first rope is attached to the left end of the rod while the second rope is attached a distance ¼L from the right end.

The tension in the second rope is:
15. A block of ice with mass m falls into a lake. After impact, a mass of ice m/5 melts. Both the block of ice and the lake have a temperature of 0º C. If L represents the heat of fusion, the minimum distance the ice fell is: