Question1

A variable reluctance sensor consists of a core, a variable air gap and an armature. The core is a steel rod of diameter 1 cm and relative permeability 100, bent to form a semi-circle of diameter 4 cm. A coil of 500 turns is wound onto the core. The armature is steel plate of thickness 0.5 cm and relative permeability 100. Assuming the relative permeability of air = 1.0 and permeability of free space = 4π × 10−7Hm−1, compute an inductance of the sensor for air gaps of 1 mm and 3 mm.

Question2

Consider elastic head-on collision between a sledge hammer with 8000 g mass and a golf ball with a 4 g mass.
The first velocity of the sledge hammer is 14 m/s, and the golf ball is at first at rest. guess the approximate final speed v2 of the golf ball.

Question3

You are driving to the grocery store at 19 m/s .You is 150 m from an intersection while the traffic light turns red. Suppose that your reaction time is 0.76 s. and that your car brakes with constant acceleration. How far are you from intersection when you begin to apply the brakes? What acceleration will bring you to rest right at the intersection? How long does it take you to stop?