Three people race each other. They all start from the same position (x = 0) and begin the race at the same time (t = 0). The person who is the first to cross the finish line at x = D will win the race. The graphs of the racers’ positions vs. times are shown below. Which statement about these racers is false?

Train A leaves Athens and heads directly toward Sparta at a constant speed of 20 km/hr. One hour later, Train B leaves Sparta and heads directly toward Athens at a constant speed of 60 km/hr. How much time elapses after train B leaves until the two trains pass each other? The distance between Athens and Sparta is 200 km.

A 2000 kg car traveling north at 60 m/s needs to stop in a distance of 300 m. What is the required (constant) acceleration?

A 1200 kg automobile moving at 25 m/s has the brakes applied with a braking force of 6000 N. How far does the car travel before it stops?

A person is pushing on the bottom crate in a stack of two crates as shown. The entire system is at rest. Which of the following statements regarding this situation is FALSE?

A horizontal, stationary plank is supported by two ropes.  The first rope is connected to the left end of the plank.  The second rope is connected to a point a distance D from the left end of the plank, somewhere between the plank’s midpoint and its right end. If you decrease the distance D by a small amount, what will happen to the magnitude of the tension in the second rope?  Assume the plank remains horizontal and stationary, and you do nothing to the first rope.

A car of mass m slides on frictionless ice with velocity 2v. It collides with a truck of mass 2m that slides on the same ice with velocity v directed in the opposite direction. The car and the truck stick together after the collision. How much kinetic energy is lost in the collision?

A uniform solid cylinder rolls without slipping across a flat surface. What fraction of its total kinetic energy is due to rotation? Icylinder = (1/2)MR2

You have a spring with k = 640 N/m connected to a mass with m = 10 kg.  You start the system oscillating and measure the velocity of the mass as it moves through the spring’s equilibrium position to be 4 m/s. At what position is the kinetic energy of the system equal to the potential energy?

A mass attached to a spring is undergoing simple harmonic motion as shown below. The surface is frictionless. The equilibrium position of the spring is indicated by the dashed line. At the point shown, the mass is at its maximum displacement from equilibrium. Which of the following statements is NOT true regarding the point shown? (“The system” refers to the system of the mass and the spring.)