Sally travels by car from one city to another. she drives for 26.0 min at 83.0 km/h, 52.0 min at 41.0 km/h, and 45.0 min at 60.0 km/h, and she spends 15.0 min eating lunch and buying gas.
what's the average speed (km/h)?
what's the total distance traveled(km)?

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.

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative

A40.0 l tank of ammonia has a pressure of 12.7 kpa. calculate the. volume of the ammonia if it’s pressure is changed to 8.4 kpa while its temperature remains constant.