Which is not true about longitudinal waves? A. High pitch sounds have higher frequencies.
B. Longitudinal waves have to travel through a medium.
C. Electromagnetic waves are longitudinal waves.
D. Sound waves are longitudinal waves.

Which type of circuit is becoming more common in residential electrical design and construction? a. hazardous-area circuit b. three-phase circuit c. 480-volt circuit d. communication circuit

The motor m applies a time-varying force of f (200 t) n, where t is in seconds. box b with mass 200 kg starts from rest, and the coefficients of kinetic and static friction are 0.2 and us 0.3 the acceleration due to gravity is g 9.8 m/s2 b 300 a) find the time ' when the box starts to move. b) calculate the speed of the crate at 3 s c) calculate the power delivered by the motor at t 3 s

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?