Answer: H
Explanation:
When beavers dam a stream they slow the movement of water. Behind the beaver dam, a pond of still water is formed. This pond is then colonized by animals and plants that typically live in lakes rather than streams.
Gravity slows the upward speed of any rising object by 9.8 m/s every second.
If the ball is tossed upward at 20 m/s, then it's at the top of its arc and its speed has dwindled to zero in (20/9.8) = 2.04 seconds.
During that time, its starting speed is 20 m/s and its ending speed is zero, so its AVERAGE speed all the way up is (1/2) (20 + 0) = 10 m/s .
Sailing upward for 2.04 seconds at an average speed of 10 m/s, the ball rises to (2.04 x 10) = <em>20.4 meters.</em>
Wave reflection occurs when waves reflect or rebound off of a surface. This is like an echo because the sound waves are reflected from a distant surface
A radio telescope is simply a telescope that is designed to receive radio waves from space. In its simplest form it has three components:
1. One or more antennas to collect the incoming radio waves. Most antennas are parabolic dishes that reflect the radio waves to a receiver, in the same way as a curved mirror can focus visible light to a point.
2. A receiver and amplifier to boost the very weak radio signal to a measurable level. These days the amplifiers are extremely sensitive and are normally cooled to very low temperatures to minimise interference due to the noise generated by the movement of the atoms in the metal (called thermal noise).
3. A recorder to keep a record of the signal. Most radio telescopes nowadays record directly to some form of computer memory disk as astronomers use sophisticated software to process and analyse the data.
