1. A popular baby toy is called a “Johnny Jump Up.” The Johnny Jump Up is a seat that a 12 month old would sit it. The seat is attached to a long spring that is connected to the frame of a door. If a 10kg baby bobs up and down with a frequency of 0.67 Hz, what is the spring constant of the spring in the Johnny Jump Up?

What are the similarities & differences between a thermistor and a light dependent resistor in physics?

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.

The direction of the current in an alternating current circuit remains constant. is direct. changes repeatedly. changes randomly.