A bullet is fired perpendicularly into a plate at an initial speed of 200 m/sec. When the bullet exits the plate, its speed is 50 m/sec. It is known that the thickness of the plate is 20 cm and the resistant force of the plate on the bullet is proportional to the square of the speed of the bullet. Determine the time that the bullet takes to pass through the plate.

Explain the doppler effect in terms of frequency, wavelength, and speed.

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)