Students are collecting data as they control the toy helicopter shown. The helicopter has a mass m and must exert a thrust of power P0 to initially move upward with a constant speed v0 . The students then cause the helicopter to exert a thrust so that a net force Fnet=2mg accelerates it upward. As the helicopter is accelerating, it has a thruster power Pf , and as it passes a height h0 it has a speed of 3v0. The ratio PfP0 is most nearly

Suppose that an electromagnetic wave which is linearly polarized along the x−axis is propagating in vacuum along the z−axis. the wave is incident on a conductor which is placed at z > 0 region of the space. the conductor has conductivity σ, magnetic permeability µ and electric permittivity ε. (a) find the characteristic time for the free charge density which dissipates at the conductor. (b) write the maxwell equations and derive the wave equation for a plane wave propagating in a conductor. (c) find the attenuation distance at which the incident amplitude reduces to e ^−1 of its initial value. (d) find the electric and magnetic fields inside the conductor. 8 (e) find the power loss per area of the incident electromagnetic wave at the surface of conductor.

In which of the following cases is work being done on an object? question 2 options: pushing against a locked door carrying a box down a corridor pulling a trailer up a hill suspending a heavy weight with a strong chain

Which one of the following research methods can show cause and effect