What is the difference between speed and velocity? A.
Speed measures an object's change in position, while velocity measures an object's change in position per unit time.
B.
Speed measures an object's change in position per unit time, while velocity measures an object's change in speed per unit time.
C.
Velocity and speed both measure an object's change in position, but velocity only depends upon the object's speed.
D.
Velocity measures an object's rate and direction of motion, and speed measures rate only.

When you turn on a battery-operated device, an electrical circuit is

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron