Explain why and how theories may be changed or replaced over time.

An object is thrown horizontally from the open window of a building. If the initial speed of the object is 20 m/s and it hits the ground 2.0 s later, from what height was it thrown? (Neglect air resistance and assume the ground is level.)

Which elements do hydrogen fuel cells combine to produce electricity?

if your car starts from rest and has an acceleration of 3.2 m/s2 how fast are you going after you have driven 20m

How does the brightness of a bulb tell you about the energy of electrons passing through it?

El Niño, La Niña, and the Walker cell are all types of A. atmospheric circulation. B. continental plates. C. ocean currents. D. air masses.

What does the speed of sound depend on? A. Medium that the sound travels through B. Acoustics C. Frequency of the sound D. Loudness of the sound

Which of these is not a source of the shock waves that lead to protostars?

Which kind of information is known about a person if that person's DNA is in a database? A. how old the person is B. where the person was probably born C. some diseases the person might have D. whether the person is likely to commit a crime

A science teacher ran a marathon. After the race she showed her students the silver blanket she was given to keep her warm. A group of students investigated how the colour of the blanket affected how much infrared radiation is absorbed

Students asked to measure the temperature of a reaction beaker recorded the following temperatures. 103.7°C, 108.4°C, 105.8°C, 104.6°C The actual temperature is 105.1°C. Which measurement is the most precise