How did people measure speed before speedometers and radar guns were invented

What do scientists use to explain an atom or the universe?

Consider two identical containers. Container A is filled with water to the top. Container B has a block of wood floating in it, but the level of the water is also at the top. Which container weighs more

The energy that powers a hurricane is derived from? a.) a stationary front. c.) funnel clouds. b.) condensation of water vapor. d.) sublimation of water.

A very long nonconducting cylinder of diameter 10.0 cm carries charge distributed uniformly over its surface. Each meter of length carries + 5.50 µC of charge. A proton is released from rest just outside the surface.

Magnetic fields interact with each other just like electric fields do. True False

A machine shovel moves dirt at the rate of 1,100 pounds of dirt 1 foot in 1 second. How many horsepower is this?

Two descriptions about physical quantities are given below: Quantity A: It is a force. Quantity B: It changes when the object travels from Earth to Earth's moon. What quantities are these most likely describing? A.

How does the tilt of Earth's axis affect how the sun's rays strike Earth?

A stone is tied to s string and whirled around in a circle at constant speed. Is the string more likely to break when the circle is horizontal or when it is vertical? Account for your answer, assuming the constant speed is the same.

Two blocks, stacked one on top of the other, slide on a frictionless horizontal surface. The surface between the two blocks is rough, however, with a coefficient of static friction equal to 0.50. The top block has a mass of 2.