You walk into the physics lab to find that your lab partner has already started the experiment. The motion of an air cart on a horizontal, frictionless air track is being studied. The cart is connected to one end of a horizontal spring, the other end of which is fixed to the air track. (See Interactive Fig. 15.4.1.) The cart's mass has been measured (m = 0.250 kg), and the spring constant has been measured ( k = 5.00 N/m). The position and velocity ofthe air cart are measured by an ultrasonic motion detector placed at one end of the air track. The sensor has been calibrated so that it reads x = 0 when the cart is at its equilibrium position. At the instant you enter the lab, which ist = 2.00 s, the position of the cart is x = 0.500 m, and the velocity of cart is v = 2.00 m/s. Snapshop at t = 2 s ultrasonic motion detector 4 Interactive Figure 15.4.1: An air cart moves on an air track and is connected to a spring